25/29
Johnny Nunez/WireImage
2004
Not all witches wear black, you know? In fact, this witch had a lacy costume that included a fake skeleton she got at a medical supply store.
26/29
Theo Wargo/WireImage
2003
Gladiator goddess or sci-fi dream? Either way, this vivacious look goes down as one of her best.
27/29
Dimitrios Kambouris/WireImage
2002
The former Victoria's Secret model was red hot, as she channeled the iconic Betty Boop.
28/29
Theo Wargo/WireImage
2001
In her second year hosting, the star went full Lady Godiva—horse and all!
29/29
DMIPhoto/FilmMagic
2000
While the model's looks have become a lot more elaborate, for her very first party she was just Heidi (as in the character from Johanna Spyri’s German novels), choosing to dress up in a dirndl "but not a tradtional dirndl," she told People. "And in those days I still did my hair and makeup by myself."