Jason Alexander is returning to sitcoms with a special guest star role on CBS’ “Young Sheldon,” Variety has learned exclusively.

Alexander will play Mr. Lundy – Medford High School’s resident drama teacher who “boldly shepherds” Sheldon (Iain Armitage) into the world of acting. He will appear in the 16th episode of “The Big Bang Theory’s” prequel’s first season, which will air this spring.

Alexander, who most famously portrayed George Costanza in sitcom “Seinfeld” for nine years in the 1990s, was most recently seen in Audience Network’s comedy, “Hit The Road.” Some of his other television credits include “Friends,” “Everybody Hates Chris,” “Curb Your Enthusiasm,” “Listen Up” and “The Grinder.”

“Young Sheldon,” which is executive produced by Chuck Lorre, Steve Molaro, Jim Parsons and Todd Spiewak, is the No. 1 new comedy in viewers, adults 18-49 and adults 25-54 and the No. 2 comedy in all of television, behind its predecessor “The Big Bang Theory.” The most recent episode saw 12.88 live+same day total viewers and 2.3 in the 18-49 demo.

“Young Sheldon” returns with new episodes Mar. 1 and the show has already been renewed for a second season.