8. Mandy
Mandy is another fan favourite character who has appeared in only 7 episodes in the entire series, all occurring during the first four seasons. She began her run on the show as the sexy lesbian assassin who blows up the plane on which Martin Belkin is aboard, as part of a plot to assassinate David Palmer. She disappears without a trace after 3 episodes, re-appearing in season 2's finale, poisoning Palmer with a contact-based toxin, and then she makes her final appearances in season four, again as a terrorist, though ends up being given a pardon for co-operating with CTU. Mandy is one of the show's few antagonists to not just remain alive, but also free, and so it would be great to see her return, because nobody should be able to escape Jack Bauer's wrath. Given her esteem among 24 fans, I don't think many would object to her return, no matter how ridiculous and contrived it might seem; she
has to die. However, actress Mia Kirshner's commitment to the show Defiance might result in yet another fleeting appearance at best.