Who would these people be the demigod children of and what would their powers be?

A friend of mine is writing a story set in an alternate universe in which Mike Tyson, Kurt Cobain, Jimmy Hendrix, Johnny Cash, Joan of Arc, Shaka Zulu, Marilyn Monroe, Eminem, and Billy Joel are demigods living in the same time period. Don't ask how this will fit together, he just wants me to gather information. Please don't say anything about how this is a dumb idea or anything, I've already pointed it out, but he's set on the idea. He says that they can be form the Norse, Egyptian, Greek, Roman, and Celtic Pantheons. He would also like ideas for what powers they might have.