Hyman Krustofsky was born to Zev Krustofsky, who had emigrated to the United States in 1902. Hyman was a respected Rabbi in Springfield's Lower East Side; his father and grandfather also having been rabbis. He was married to a woman named Rachel, and the marriage produced one son, Herschel Krustofsky. Rachel died prior to Herschel's adolesence, and Hyman had guided Herschel into following his footsteps. Herschel, however, thought of being a clown, which angered Hyman as he figured life was too serious for such antics. Herschel secretly worked on comedy acts, and got his first laugh at the yeshiva school doing an impersonation of his father. Hyman found out about this and worked to discourage his son. Herschel got a gig performing antics for a rabbi's convention, where Hyman was in attendance. When a jocose rabbi pulled a prank on Herschel by spraying him with seltzer, this washed off the clown makeup. An angered Hyman disinherited Herschel.
Years later, Bart Simpson and Lisa Simpson found out about the estrangement between Hyman and Herschel (now better known as Krusty the Clown) and waged a campaign to convince Hyman to reunite with his son by quoting passages of Jewish scripture. After several attempts, Bart finally convinced Hyman by quoting Sammy Davis Jr.. Hyman met his son backstage on The Krusty the Clown Show, and the two embraced after many years. Hyman Krustofsky appeared in front of the audience playfully throwing a pie at Krusty.
In a later, nonspeaking appearance, Homer appealed to Rabbi Krustofsky to pay for a quadruple bypass surgery. Typical to Homer's ineptitude, he claims to be Jewish and his claim to doing so is by wanting to see "Fiddler on the Roof". Krustofsky looks surprised when Homer out of the blue asks for $40,000, and it is implied that he was refused, although the rabbi did give him a dreidel, which Homer is later playing with.
In "Today, I Am a Clown," when Krusty and Bart and Lisa Simpson go to Rabbi Krustofsky to ask why Krusty never had a Bar Mitzvah when he was thirteen, Krusty's father explains it was because he was afraid that Krusty, being very mischievous as a kid, would make a mockery of the whole ceremony. Homer Simpson was given a show during Krusty's time-slot on Saturdays (the Sabbath day for Jews) and it was so popular that Krusty's show was cancelled. In a move of desperation, he decided to televise his Bar Mitzvah. It proved to be extremely successful, but disappoints Hyman. Krusty, feeling guilty, tells his dad after the show that he wants to have a real Bar Mitzvah the traditional way at a Jewish temple, which pleases Rabbi Krustofsky. The two have a much simpler manhood ceremony. He died during the first episode of Season 26, "Clown in the Dumps."
Mason won an Emmy Award for his performance in "Like Father, Like Clown."
The episode "Like Father, Like Clown" was intended to spoof the film The Jazz Singer, but it also made reference to Jackie Mason, whose father was a rabbi. Mason broke with the family tradition to pursue a career in comedy, however he did undergo rabbicinal training in the event his comedian's career did not pan out, he could fall back on a job as a rabbi.
- His last words were "As for you, son, if you want to know my honest opinion of you, you've always been.. eh.".