Q: In the comic strip Peanuts, what is Violet's last name?
[In case the img source for this comic goes dark later: it is Gray.]
Characters with last names that we know:
Charlie (and Sally) Brown (of course)
Linus and Lucy (and Rerun) Van Pelt
and now: Violet Gray
There are a few other characters with known last names. "Peppermint" Patty has one, Reichardt.