Casper's family

Casper had many relatives that appeared on many franchises.

Parents
In earlier Cartoon, "Casper's Birthday Party," Casper's mother and father were shown. His mother was shown to love him and his father the same. They were actually both said to be natural born ghosts and its shown that they love their son the way he is.

In Casper, Casper's parents are revealed to have the last name, McFadden. His father, JT McFadden was the younger brother of the Ghostly Trio and his wife, Mrs. McFadden, had a dress that Casper let Kat Harvey wear.

Siblings
Casper has no siblings, but it is heavily implied that the first iteration of the Ghostly Trio were his elder brothers.

Grandparents
Casper's grandmother was mentioned in The Spooktacular New Adventures of Casper. In Casper's Scare School, Casper has  agrandmother who kisses him a lot.