Enjoyed a long career on Broadway; active there from 1916-48, returning in 1952 for one more production (the hit comedy, "Time Out for Ginger," starring Melvyn Douglas) after being blacklisted in Hollywood. Although he was an infrequent stage director, he continued to act and occasionally choreograph throughout his career.
He was blacklisted during the "Red Scare" of the early 1950s, though charges against him were never proven. He declared under oath that he was never a member of the Communist Party and despite co-star Gertrude Berg's efforts to keep him, "Molly" (1949)'s sponsor General Foods and CBS executives made it clear that either he'd leave or the show would be yanked off the air. With its switch to NBC in February 1952, Loeb was gone and his acting career went with it. He became depressed and embittered, committing suicide with an overdose of barbituates in 1955.