Legendary theater star Len Cariou has walked out on his latest show, “Harry Townsend’s Last Stand,” according to its producers — who say they’ll have to close the play as a result.

Playwright George Eastman’s off-Broadway two-hander opened in December co-starring Cariou and Craig Bierko as his son. But lead producer Dennis Grimaldi said on Monday that the show must fold after 15 previews and 103 shows.

“Cariou is breaking his contractual obligation, refusing to perform past March 3,” exasperated reps for the show told Page Six. With Bierko ending his run, “Cariou is refusing to rehearse with a cast replacement [David Lansbury] or perform with an understudy. His actions are causing [the show] to close prematurely,” they said. Producers say they’ll lose money, and “Len gave his notice on Friday … leaving no time to find a replacement.”

They claim Cariou, 80, had a six-month contract until mid-May with “no outs.” Cariou — who starred with “a touching mix of braggadocio and vulnerability” in the show, according to a New York Times review — originated the role of “Sweeney Todd” on Broadway in 1979 and won a Tony. His reps did not get back to us.