If Ellen DeGeneres is known for anything, aside from her killer dance moves, of course, it's her extremely innovative Halloween costumes. She's known to go all out for Halloween, never failing to get into the spirit of the spooky holiday with a well-timed homage to an iconic figure, a concept or whatever is the big thing at that moment in pop culture. This yea, she dressed up as Sia and guest Heidi Klumdonned a nude leotard and writhed around as the artist's No. 1 dance muse, Maddie Ziegler.