Thomas Jeffrey Hanks was born in Concord, California on July 9, 1956, the son of hospital worker Janet Marylyn (née Frager; died 2016) and itinerant cook Amos Mefford Hanks. His mother was of Portuguese descent (her family's surname was originally "Fraga"), while his father had English ancestry. His parents divorced in 1960. Their three oldest children, Sandra (later Sandra Hanks Benoiton, a writer), Larry (an entomology professor at the University of Illinois at Urbana–Champaign), and Tom, went with their father, while the youngest, Jim (who also became an actor and filmmaker), remained with their mother in Red Bluff, California. In his childhood, Hanks' family moved often; by the age of 10, he had lived in 10 different houses.

While Hanks' family religious history was Catholic and Mormon, he has characterized his teenage self as being a "Bible-toting evangelical" for several years. In school, he was unpopular with students and teachers alike, later telling Rolling Stone magazine, "I was a geek, a spaz. I was horribly, painfully, terribly shy. At the same time, I was the guy who'd yell out funny captions during filmstrips. But I didn't get into trouble. I was always a real good kid and pretty responsible." In 1965, his father married Frances Wong, a San Francisco native of Chinese descent. Frances had three children, two of whom lived with Hanks during his high school years. Hanks acted in school plays, including South Pacific, while attending Skyline High School in Oakland, California.

Hanks was married to American Actress Samantha Lewes from 1978. They had one son, actor Colin Hanks (born 1977), and one daughter, Elizabeth Hanks (born 1982).

In 1979, Hanks moved to New York City, where he made his film debut in the low-budget slasher film He Knows You're Alone (1980) and landed a starring role in the television movie Mazes and Monsters. Early that year, he was cast in the lead, Callimaco, in the Riverside Shakespeare Company's production of Niccolò Machiavelli's The Mandrake, directed by Daniel Southern. The following year, Hanks landed one of the lead roles, that of character Kip Wilson, on the ABC television pilot of Bosom Buddies. He and Peter Scolari played a pair of young advertising men forced to dress as women so they could live in an inexpensive all-female hotel. Hanks had previously partnered with Scolari on the 1970s game show Make Me Laugh. After landing the role, Hanks moved to Los Angeles. Bosom Buddies ran for two seasons, and, although the ratings were never strong, television critics gave the program high marks. "The first day I saw him on the set," co-producer Ian Praiser told Rolling Stone, "I thought, 'Too bad he won't be in television for long.' I knew he'd be a movie star in two years." However, although Praiser knew it, he was not able to convince Hanks. "The television show had come out of nowhere," Hanks' best friend Tom Lizzio told Rolling Stone.

In 1981, Hanks met Actress Rita Wilson on the set of TV comedy Bosom Buddies (1980-1982). They were reunited in 1985 on the set of Volunteers.

Bosom Buddies and a guest appearance on a 1982 episode of Happy Days ("A Case of Revenge," in which he played a disgruntled former classmate of Fonzie) prompted Director Ron Howard to contact Hanks. Howard was working on the film Splash (1984), a romantic comedy fantasy about a mermaid who falls in love with a human. At first, Howard considered Hanks for the role of the main character's wisecracking brother, a role that eventually went to John Candy. Instead, Hanks landed the lead role in Splash, which went on to become a surprise box office hit, grossing more than US$69 million. He also had a sizable hit with the sex comedy Bachelor Party, also in 1984. In 1983–84, Hanks made three guest appearances on Family Ties as Elyse Keaton's alcoholic brother, Ned Donnelly.

With Nothing in Common (1986) – a story of a young man alienated from his father (played by Jackie Gleason) – Hanks began to extend himself from comedic roles to dramatic roles. In an interview with Rolling Stone magazine, Hanks commented on his experience: "It changed my desires about working in movies. Part of it was the nature of the material, what we were trying to say. But besides that, it focused on people's relationships. The story was about a guy and his father, unlike, say, The Money Pit, where the story is really about a guy and his house."

Hanks married Wilson in 1988. They have two sons. The oldest, Chester Marlon "Chet" Hanks, had a minor role as a student in Indiana Jones and the Kingdom of the Crystal Skull and released a rap song in 2011. Their youngest, Truman Theodore, was born in 1995.

Hanks then suffered a run of box-office underperformers: The 'Burbs (1989), Joe Versus the Volcano (1990), and The Bonfire of the Vanities (1990). In the last, he portrayed a greedy Wall Street figure who gets enmeshed in a hit-and-run accident. 1989's Turner & Hooch was Hanks' only financially successful film of the period.

Hanks climbed back to the top again with his portrayal of a washed-up baseball legend turned manager in A League of Their Own (1992). Hanks has stated that his acting in earlier roles was not great, but that he subsequently improved. In an interview with Vanity Fair, Hanks noted his "modern era of moviemaking ... because enough self-discovery has gone on ... My work has become less pretentiously fake and over the top". This "modern era" began in 1993 for Hanks, first with Sleepless in Seattle and then with Philadelphia. The former was a blockbuster success about a widower who finds true love over the radio airwaves. Richard Schickel of TIME called his performance "charming," and most critics agreed that Hanks' portrayal ensured him a place among the premier romantic-comedy stars of his generation.

In Philadelphia, he played a gay Lawyer with AIDS who sues his firm for discrimination. Hanks lost 35 pounds and thinned his hair in order to appear sickly for the role. In a review for People, Leah Rozen stated, "Above all, credit for Philadelphia's success belongs to Hanks, who makes sure that he plays a character, not a saint. He is flat-out terrific, giving a deeply felt, carefully nuanced performance that deserves an Oscar." Hanks won the 1993 Academy Award for Best Actor for his role in Philadelphia. During his acceptance speech, he revealed that his high school drama Teacher Rawley Farnsworth and former classmate John Gilkerson, two people with whom he was close, were gay.

Hanks followed Philadelphia with the 1994 hit Forrest Gump which grossed a worldwide total of over $600 million at the box office. Hanks remarked: "When I read the script for Gump, I saw it as one of those kind of grand, hopeful movies that the audience can go to and feel ... some hope for their lot and their position in life ... I got that from the movies a hundred million times when I was a kid. I still do." Hanks won his second Best Actor Academy Award for his role in Forrest Gump, becoming only the second actor to have accomplished the feat of winning consecutive Best Actor Oscars. (Spencer Tracy was the first, winning in 1937–38. Hanks and Tracy were the same age at the time they received their Academy Awards: 37 for the first and 38 for the second.)

Hanks made his directing debut with his 1996 film That Thing You Do! about a 1960s pop group, also playing the role of a music Producer. Hanks and Producer Gary Goetzman went on to create Playtone, a record and film production company named after the record company in the film.

In 1998, Hanks' next project was no less expensive. For Saving Private Ryan, he teamed up with Steven Spielberg to make a film about a search through war-torn France after D-Day to bring back a soldier. It earned the praise and respect of the film community, critics, and the general public. It was labeled one of the finest war films ever made and earned Spielberg his second Academy Award for direction, and Hanks another Best Actor nomination. Later that year, Hanks re-teamed with his Sleepless in Seattle co-star Meg Ryan for You've Got Mail, a remake of 1940's The Shop Around the Corner. In 1999, Hanks starred in an adaptation of the Stephen King novel The Green Mile. He also returned as the voice of Woody in Toy Story 2, the sequel to Toy Story. The following year, he won a Golden Globe for Best Actor and an Academy Award nomination for his portrayal of a marooned FedEx systems analyst in Robert Zemeckis's Cast Away.

Hanks studied theater at Chabot College in Hayward, California, and transferred to California State University, Sacramento, two years later. During a 2001 interview with Bob Costas, Hanks was asked whether he would rather have an Oscar or a Heisman Trophy. He replied he would rather win a Heisman by playing halfback for the California Golden Bears. He told New York magazine in 1986, "Acting classes looked like the best place for a guy who liked to make a lot of noise and be rather flamboyant. I spent a lot of time going to plays. I wouldn't take dates with me. I'd just drive to a theater, buy myself a ticket, sit in the seat and read the program, and then get into the play completely. I spent a lot of time like that, seeing Brecht, Tennessee Williams, Ibsen, and all that."

In 2001, Hanks helped direct and produce the Emmy-Award-winning HBO miniseries Band of Brothers. He also appeared in the September 11 television special America: A Tribute to Heroes and the documentary Rescued From the Closet. He then teamed up with American Beauty Director Sam Mendes for the adaptation of Max Allan Collins's and Richard Piers Rayner's graphic novel Road to Perdition, in which he played an anti-hero role as a hitman on the run with his son. That same year, Hanks collaborated once again with Director Spielberg, starring opposite Leonardo DiCaprio in the hit biographical crime drama Catch Me If You Can, based on the true story of Frank Abagnale, Jr. The same year, Hanks and his wife Rita Wilson produced the hit movie My Big Fat Greek Wedding. In August 2007, he along with co-producers Rita Wilson and Gary Goetzman, and Writer and star Nia Vardalos, initiated a legal action against the production company Gold Circle Films for their share of profits from the movie. At the age of 45, Hanks became the youngest-ever recipient of the American Film Institute's Life Achievement Award on June 12, 2002.

In 2004, he appeared in three films: The Coen brothers' The Ladykillers, another Spielberg film, The Terminal, and The Polar Express, a family film from Zemeckis for which Hanks played multiple motion capture roles. In a USA Weekend interview, Hanks discussed how he chooses projects: "[Since] A League of Their Own, it can't be just another movie for me. It has to get me going somehow ... There has to be some all-encompassing Desire or feeling about wanting to do that particular movie. I'd like to assume that I'm willing to go down any avenue in order to do it right". In August 2005, Hanks was voted in as vice President of the Academy of Motion Picture Arts and Sciences.

In 2006, the Space Foundation awarded Hanks the Douglas S. Morrow Public Outreach Award, given annually to an individual or organization that has made significant contributions to public awareness of space programs.

In 2007, Hanks starred in Mike Nichols's film Charlie Wilson's War (written by Screenwriter Aaron Sorkin) in which he played Democratic Texas Congressman Charles Wilson. The film opened on December 21, 2007, and Hanks received a Golden Globe nomination. In the comedy-drama film The Great Buck Howard (2008), Hanks played the on-screen father of a young man (played by Hanks' real-life son, Colin) who chooses to work as road manager for a fading mentalist (John Malkovich). His character was less than thrilled about his son's career decision. In the same year, he executive produced the musical comedy, Mamma Mia and the miniseries, John Adams.

In June 2006, Hanks was inducted as an honorary member of the United States Army Rangers Hall of Fame for his accurate portrayal of a captain in the movie Saving Private Ryan; Hanks, who was unable to attend the induction ceremony, was the first actor to receive such an honor. In addition to his role in Saving Private Ryan, Hanks was cited for serving as the national spokesperson for the World War II Memorial Campaign, for being the honorary chairperson of the D-Day Museum Capital Campaign, and for his role in writing and helping to produce the Emmy Award–winning miniseries, Band of Brothers. On March 10, 2008, Hanks was on hand at the Rock and Roll Hall of Fame to induct The Dave Clark Five.

Hanks' next endeavor, released on May 15, 2009, was a film adaptation of Angels & Demons, based on the novel of the same name by Dan Brown. Its April 11, 2007, announcement revealed that Hanks would reprise his role as Robert Langdon, and that he would reportedly receive the highest salary ever for an actor. The following day he made his 10th appearance on NBC's Saturday Night Live, impersonating himself for the Celebrity Jeopardy Sketch. Hanks produced the Spike Jonze film Where The Wild Things Are, based on the children's book by Maurice Sendak in 2009.

In 2010, Hanks reprised his voice role of Woody in Toy Story 3, after he, Tim Allen, and John Ratzenberger were invited to a movie theater to see a complete story reel of the movie. The film went on to become the first animated film to gross a worldwide total of over $1 billion as well as the highest-grossing animated film at the time. He also was executive Producer of the miniseries, The Pacific.

In 2011, he directed and starred opposite Julia Roberts in the title role in the romantic comedy Larry Crowne. The movie received poor reviews, with only 35% of the 175 Rotten Tomatoes reviews giving it high ratings. Also in 2011, he starred in the drama film Extremely Loud and Incredibly Close. In 2012, he voiced the character Cleveland Carr for a web series he created titled Electric City. He also starred in the Wachowskis-directed film adaptation of the novel of the same name, Cloud Atlas and was executive Producer of the miniseries Game Change.

On October 7, 2013, on The Late Show with David Letterman, Hanks announced that he has Type 2 diabetes.

Before marrying Wilson, Hanks converted to the Greek Orthodox Church, the religion of Wilson and her family. He said, "I must say that when I go to church—and I do go to church—I ponder the mystery. I meditate on the 'why?' of 'why people are as they are' and 'why bad things happen to good people,' and 'why good things happen to bad people' ... The mystery is what I think is, almost, the grand unifying theory of all mankind."

In March 2015, Hanks appeared in the Carly Rae Jepsen music video for "I Really Like You", lip-syncing most of the song's lyrics as he goes through his daily routine. His next film was the Steven Spielberg-directed historical drama Bridge of Spies, in which he played Lawyer James B. Donovan who negotiated for the release of pilot Francis Gary Powers by the Soviet Union in exchange for KGB spy Rudolf Abel. It was released in October 2015 to a positive reception. In April 2016, Hanks starred as Alan Clay in the comedy-drama A Hologram for the King, an adaptation of the 2012 novel of the same name.

Hanks starred as airline captain Chesley Sullenberger in Clint Eastwood's Sully, which was released in September 2016. He next reprised his role as Robert Langdon in Inferno (2016), and co-starred alongside Emma Watson in the 2017 science fiction drama The Circle. He voiced David S. Pumpkins in The David S. Pumpkins Animated Halloween Special, which aired October 28, 2017, on NBC, a character he had portrayed in episodes of Saturday Night Live.

In March 2018, Hanks was cast to portray Fred Rogers in Marielle Heller's biographical film You Are My Friend.