Will Smith's father on Fresh Prince.

Louise Jefferson's father on The Jeffersons.

Joe and Brian Hackett's mother on Wings.

Cliff Clavin's father on Cheers

The Evans family on Good Times had numerous relatives who came out of the woodwork (many of them turned out to be drinkers, robbers, fugitives, etc). I think the only one who was on more than once was James Evans' long lost dad. (He was probably the most normal of all the relatives, and was a clean, upstanding citizen.)

After the parents left on The Waltons, Cousin Rose showed up with her grandkids. I believe that was the same lady who played Mrs. Boss Hogg on Dukes of Hazzard and Suzanne Somers' mom on Step by Step, Peggy Rea. Wasn't she also on Grace Under Fire??

There was also Harriette and Rachel's long lost father on Family Matters, who suddenly showed up. Carl and Harriette also had a troublemaking nephew who came to visit, stole a car and got Eddie and Steve involved in the whole mess.

I guess this would be the opposite of the Chuck Cunningham Syndrome, right Janice??

alex meade, daniel meade's brother who becomes alexis meade, alas a transexual who comes back from the dead as a woman in ugly betty

On 'Mama's Family', Carl's (Mama's dead husband) brother, Roy, comes to visit. He didn't show up for his brothers funeral and is known to be a drifter.

Chico's father (who was supposed to be dead) showed up and told Chico the truth about himself and why he left the family. It was a touching episode and is especially sad because it's so close to the end of Freddie Prinze's life.