Mace Windu was a memorable character, but was also a character that was introduced back when Anakin was a small child -- fast forward 60 years...is Mace even still alive?
"Yeah, I'd love to be a part of that," he says. "I think it'd help people come back to the franchise, to have some familiar characters before they start introducing all the new ones."Source: The Northern Star
So you wouldn't mind being a ghost? "I don't know why I'd have to be a ghost. I'm a Jedi! I fell out of a window and they took my hand off. I could show up as a one-handed Jedi - alive!"