During the 1950s and 1960s, Crothers made guest appearances on numerous primetime shows, including Alfred Hitchcock Presents, The Defenders, Have Gun – Will Travel, Death Valley Days, Rescue 8, The Investigators, Zane Grey Theater, Studio One, Playhouse 90, Kraft Television Theatre, and Goodyear Playhouse. His later daytime television credits included First Ladies Diaries: Martha Washington.

Born in Cincinnati, Ohio and raised in New York City, Crothers graduated from Birch Wathen School in 1958. His passion for performing emerged at the early age of nine. Crothers auditioned and won a role on the religious television show Lamp Unto My Feet. At the time, his father was a production supervisor on the show. Unbeknownst to him, his son auditioned for the show under a different name, apparently done as a practical joke. Nevertheless, by the age of twelve, he was taking Broadway bows alongside Burgess Meredith for his stage debut in 1954 in The Remarkable Mr. Pennypacker at the Coronet Theatre in New York City.

He graduated Harvard University a Phi Beta Kappa in 1962. In 1966, Crothers returned to Broadway in a starring role opposite Joan Van Ark in Barefoot in the Park, which he worked on simultaneously with his stint on Dark Shadows. From 1966-1969, he played Joe Haskell, boyfriend of Carolyn Stoddard (Nancy Barrett) and later boyfriend of Maggie Evans (Kathryn Leigh Scott). During the 1795 storyline, he played Lt. Nathan Forbes, a devious naval officer who blackmailed his way into the Collins family. After Nathan Forbes was killed off, Crothers' main character, Joe, was bitten by the vampiric Angélique and placed under her thrall. Haunted by the apparition of his deceased cousin Tom (a victim of vampire Angélique) and unable to cope with the revelation that Tom's twin brother Chris was a werewolf, Joe slowly lost touch with reality and was sent to a mental hospital by Maggie. He was never seen again and was mentioned only once in a later episode.

From 1969-1971, he played twice-married cheat and liar Ken Stevens #2 on the CBS serial The Secret Storm. Several of his 1971 episodes have been preserved by UCLA's TV Archives, though the magnetic VHS tapes are awaiting digital transfer and are not available for viewing by the public. From 1972-1976, he played concert pianist-turned-newspaper Editor Julian Cannell on Somerset. From 1977-1984, he made it big with another soap opera role: Dr. Miles Cavanaugh on ABC's The Edge of Night, for which he was twice nominated as Best Actor at the Daytime Emmy Awards in 1982 and 1983. He played that role until the series went off the air on December 28, 1984. In 1985, his final role was on Santa Barbara as both Jack Lee, a prominent attorney, and his villainous lookalike cousin Jerry Cooper, who had locked Jack in a dungeon and was posing as him.

On November 6, 1985, Crothers died from lymphoma in Los Angeles at the age of 44. His remains were cremated and scattered in Lake George, New York.

Crothers' soap opera fame helped draw attention to the ground-breaking off-Broadway play Torch Song Trilogy. The play made major stars of its Writer (and lead performer) Harvey Fierstein and castmates Estelle Getty and Matthew Broderick—but when it premiered, Crothers was better known than any of them and received star billing on posters, playbills, and even the tickets. Fierstein played Arnold, a world-weary drag queen; Crothers played Arnold's bisexual lover, Ed. He left the cast when Torch Song transferred to Broadway. Brian Kerwin played Ed in the film version.