AFTER seeing the “The Normal Heart” on Broadway last June, three teenagers from Minnesota were in a frenzy explaining why they had chosen the play. “Sheldon!” they all shouted, naming the socially clueless lead character on the CBS hit comedy “The Big Bang Theory” played by Jim Parsons, who had a small role in the play. 

 

Here was celebrity casting in action, yet it had unintended consequences: the teenagers hadn’t known that the show was about gay men dying of AIDS, and they left disappointed that Mr. Parsons wasn’t acting as outrageously pompous as Sheldon, a role that earned him Emmy Awards in 2010 and 2011.

 

Not only is he dealing with the shadow of Sheldon again, but also that of a certain actor named Jimmy Stewart. Mr. Parsons is leading a Broadway cast for the first time, in a revival of “Harvey,” the Pulitzer Prize-winning comedy from 1944 about the sweet-natured Elwood P. Dowd and his invisible friend, the title character, a 6-foot-tall rabbit. The show ran on Broadway for four years, opening with Frank Fay as the lead. Stewart later followed as Elwood before bringing him to wider fame in the 1950 film, for which he was nominated for an Oscar. He reprised the role in 1970, the only previous revival on Broadway of this play, which became feared for the task of taking on The Jimmy Stewart Role.

 

While Mr. Parsons is keenly aware that both Sheldon and Stewart are indelible, he has also drawn confidence from acting techniques and instincts that have served him well for more than 20 years, since choosing his career after performing in the farce “Noises Off” in high school.

 

“People may not like me as Elwood, people may say ‘I enjoyed Jimmy Stewart more,’ ” he said recently, over coffee at a Midtown Mahattan hotel. “There’s nothing I can do about that. But I have to come in and take a stand on the performance, as it were.”