Robert Morse, whose impish, gap-toothed grin and expert comic timing made him a Tony-winning Broadway star as a charming corporate schemer in the 1961 musical “How to Succeed in Business Without Really Trying,” who later won another Tony for his portrait of the writer Truman Capote in “Tru,” and who capped his long career with a return to the corporate world on the television series “Mad Men,” died April 20 at his home in Los Angeles. He was 90.

“How to Succeed” ran for more than 1,400 performances and won seven Tony Awards, including for Mr. Morse as best actor in a musical, as well as the Pulitzer Prize for drama. A 1967 film adaptation with Mr. Morse was a hit as well, and the show has been revived twice on Broadway.

In 2007, he was cast as the eccentric head of an advertising agency in the acclaimed AMC series “Mad Men.” The role brought him five Emmy nominations. Although the role of Bertram Cooper was straight drama, Mr. Morse got to return to his musical comedy roots in the spring of 2014 when the character died and then reappeared in a fantasy song-and-dance sequence.

“What a send-off!” Mr. Morse said of the opportunity to shine in the spotlight. “It was an absolute love letter.”