The television universe is split into two neat categories: hour-long dramas and half-hour sitcoms. There are rules that govern each. On dramas, people can die. On sitcoms, deaths and disappearances aren’t supposed to happen. The rare instances when they do is the topic of this episode of Mobituaries.

On a couple of classic sitcoms, a main character simply disappeared with no explanation. This phenomenon has a name: “Chuck Cunningham Syndrome,” named after the older brother on Happy Days. Chuck appeared in the show’s first and second seasons, mostly walking through scenes and bouncing a basketball. Then, suddenly and abruptly, he completely vanished at the start of the third. Breakout star Henry Winkler’s character Fonzie became the defacto older brother figure. No one mentioned the disappearance. They carried on as if he never existed. The parents on the show even referred to their two children, instead of three.

A generation later, Judy Winslow, the youngest daughter on Family Matters, met the same fate. She appeared as a flower girl in a wedding-themed episode, then was never mentioned again. Actress Jamee Foxworth who played Judy recalls that she got fewer and fewer lines as the show focused on its now-classic character, Steve Urkle.

Sometimes, in the sitcom universe, the character stays, but the actor playing him disappears. The most famous instance of this happened in the 60s sitcom Bewitched, a show about a wife with magical powers and her husband’s anxieties about them. The original husband in the show was played by Dick York in seasons one through five . Toward the end of the fifth season, York struggled with a back injury which led to his hospitalization and, ultimately, his retirement from the show. They replaced York with Dick Sargent, never acknowledging to the audience that the actor playing the series male lead had changed. The show continued for another three seasons, but the writers sensed a chemistry shift between the two leads afterwards, and focused more on secondary characters.

Other sitcom characters that underwent a notable actor switcheroo include Aunt Viv on The Fresh Prince of Bel-Air and Becky on Rosanne.

But in the rarest of sitcom instances, characters do die as part of the plot. One of the most bizarre sitcom deaths was the demise of Valerie in the late 80’s family sitcom called Valerie. After two seasons on the show, star Valerie Harper asked for a raise. Refusing to yield to the star’s salary demands, TV executives killed off her character. The third season opens six months after Valerie’s fictional automobile accident death. The show brought in actress Sandy Duncan to play the role of the father’s sister to act as a surrogate mom, effectively replacing Valerie on the show. The show even changed titles, first moving to Valerie’s Family: The Hogans and then to The Hogan Family, nixing Valerie altogether.

While dramas like The Sopranos and Game of Thrones build story lines and fan bases, around high body counts, most of the dearly departed on these dramas quickly fade into the pop culture ether. If Tony Soprano had whacked Chuck Cunningham, the character would never have anchored an entire episode of Mobituaries. But somewhere out there in the sitcom universe, Chuck is still bouncing a basketball and we’re still talking about him.