Landesberg was born November 23, 1936, in the Bronx, New York, to a milliner mother and a grocery store-owner father. He was part of improv group New York Stickball Team, which performed several shows that were aired on cable television shortly after Barney Miller went off the air.
Landesberg was a member of the cast of the 1974 CBS situation comedy Paul Sand in Friends and Lovers. He made guest appearances on the TV shows The Tonight Show, The Rockford Files, Law & Order, Saturday Night Live, The Golden Girls, Ghost Whisperer, That '70s Show and Everybody Hates Chris. He starred in Starz's original show Head Case as Dr. Myron Finkelstein. He appeared in the motion pictures Wild Hogs, Leader of the Band, and Forgetting Sarah Marshall.
Throughout his career, Landesberg was noncommittal about his age and year of birth. At the time of his death, many news outlets mistakenly reported his age as 65; some never corrected that story. In acknowledging that he was actually nine years older than he had long claimed, his daughter Elizabeth said he had provided varying birth dates over the years. "He got kind of a late start in show Business," she explained, "so he tried to straddle the generations. He fooled the whole world. People were surprised to think he was even 65." Landesberg commented on the issue in a 1979 Washington Post profile for which he refused to give his age:
Landesberg died from colon cancer on December 20, 2010, aged 74. He was survived by his wife Nancy Ross Landesberg and a daughter Elizabeth.
