 Mandy is the longest running villain to appear on the series. She  made her first appearance in the first three episodes of Season 1  working for Ira Gaines, and returned in Season 2s finale for a  cameo appearance where she tries to assassinate David Palmer. She  returns again for the last three episodes of Season 4. Mandy was  also originally intended to appear in Season 5, but was replaced by  another character.