[Warning: this story contains spoilers spanning the entire run of 24, from the show's first season to the final seconds of the Live Another Day limited series.]

Over the course of eight proper seasons, one television movie and a limited event series, 24 became known for a few key elements: the real-time thriller format, Kiefer Sutherland as the iconic counterterrorism agent Jack Bauer...and the show's serious mole problem.?

Every single season of the Fox action series featured one or more turncoats, often emerging completely out of left field, some more successful than others — both in terms of their actions on the show, and how well the plot twists landed with the audience. The show's fictional Counter Terrorist Unit had such an astonishing problem with employing traitorous sleeper agents, that it was deactivated for a time during season seven. Even then, more moles emerged within the FBI, the CIA, the White House and beyond.

When 24: Legacy debuts, it arrives without one of the show's key ingredients: Bauer. But even if Sutherland is too busy playing president on Designated Survivor, the new iteration of his signature series isn't likely to ditch the moles. Before Legacy adds to the roster, here's how The Hollywood Reporter ranks the moles seen throughout 24 history. But first, some clarifications.

For the sake of this list, these moles are all characters who were presented to the audience in one light, only for a later reversal to fundamentally alter our perception of that character. That means we can't count the many times Bauer infiltrated terrorist cells, since the audience knows the side he's on at the end of the day. (Besides, Bauer wins every list he's on. Kind of ruins the suspense, no?) Likewise, the stunning season-two twist of Mike Novick (Jude Ciccolella) betraying David Palmer (Dennis Haysbert), as well as President Charles Logan (Gregory Itzin) secretly spearheading season five's terrorist plot, can only count as honorable mentions. Though both betrayals are fantastic and very memorable within 24 lore, it's less a mole situation and more a progression of the characters we've known them to be from their very first scenes. Final note: while most moles come with dark purposes, there's at least one major exception to the rule.

With all that out of the way, mole patrol is officially underway.

15. The Bauer Family

With the exception of a few classic Bauerisms, season six of 24 is a complete wash, without question the least successful iteration of the show. Assign the blame as you like, as long as a healthy portion is reserved for the twist that Jack's father Phillip (James Cromwell) and brother Graem (Paul McCrane) are terrorist masterminds of the highest magnitude. It added an unbearable level of soap usually reserved for the show's angsty teen subplots, but rarely for the Bauer story. And with all due respect to Cromwell, it defies explanation why 24 would bother telling any story about Jack's dad without casting Kiefer Sutherland's real-life father, Donald, in the role. While it's the lowest-ranked of the moles, the Bad Bauer twist has to be high on the list of the show's greatest creative misfires.

14. Reed Pollock

Surprise! Another entry from the show's ill-conceived sixth season. Now batting: Reed Pollock (Chad Lowe), the ambitious White House Deputy Chief of Staff who successfully orchestrates the assassination of President Wayne Palmer (D.B. Woodside)…but not without getting arrested for treason. The Pollock plot came out of nowhere, needlessly drawing more blood from the President Palmer stone. (Although Wayne's final fate is never revealed on the show, an in-continuity newspaper clipping reveals he died from the wounds he sustained on Day 6.) As Reed, Lowe turned in one of the most grating and sniveling performances in the show's history. There's a compliment in there somewhere.

13. Spenser Wolff

This hotshot CTU analyst was introduced in season five as a love interest for Chloe O'Brian (Mary Lynn Rajskub), but was quickly escorted from the scene as a moley-moley. (In his defense, he was just unwittingly following another mole's orders.) Nothing massively offensive about the character, but nothing that separates him from the pack. A perfectly bland mole, with an admittedly cool name.

12. Marianne Taylor

Back in season four, Aisha Tyler enjoyed a quick arc as a tough-as-nails CTU analyst named Marianne Taylor. As it turned out, Marianne wasn't just hard on her colleagues because it was fun; she was actually working for terrorist Habib Marwan (Arnold Vosloo) against CTU's best interests. Marianne was the first genuine CTU mole since season one, exiting the series via an unceremonious shotgun blast.

11. Sean and Erika

It's hard to imagine Billy Walsh of Entourage fame appearing on 24, unless he was playing some sort of drug lord in an unwatchable Kim Bauer (Elisha Cuthbert) subplot. Nevertheless, actor Rhys Coiro did appear on 24, starring in the show's seventh season as Sean Hillinger, a crooked FBI agent secretly working with a terrorist cell against the bureau. Sean had a Bonnie to his Clyde in the form of Erika (Ever Carradine), his co-conspirator and lover — and someone he eventually killed and accused as the mole. The ruse only worked so long before Sean was arrested and quickly swept up in the tide of forgotten 24 subplots.

10. Gedge and Vossler

Let's view these two Secret Service agents as the ambassadors of the nefarious plot to take down President Allison Taylor (Cherry Jones) during season seven. Brian Gedge and Edward Vosseler, played by Warren Kole and Mark Kiely, respectively, were pretty paint-by-the-numbers villains as far as it goes on 24, but earn some marks for their memorable deaths: Vosseler stabbed in the gut by Bauer, and Gedge brutally beaten by a mostly paralyzed First Gentleman Henry Taylor (Colm Feore).

9. Steve Navarro

You can take America out of 24, but you can't take away the moles. Such was the lesson learned during 24: Live Another Day, the London-set limited series starring some notable new additions to the 24 mythos, including Benjamin Bratt as a high-ranking CIA operative named Steve Navarro. He was also a mole, because of course he was. Bad Bratt is better than no Bratt.

8. Dana Walsh

At the time it aired, season eight was a frustrating rehash of the show's earlier successes. On reflection, it reads more like a celebration of the show's greatest hits. In that regard, Battlestar Galactica veteran Katee Sackhoff as traitorous CTU agent Dana Walsh was something of a second coming of the Nina Myers modeled mole. Sure, Dana's story barely makes any sense at all when trying to reconcile her mole status with her secret pre-CTU past. And yes, we had basically seen it all before with the Nina twist. But we hadn't seen it in the capable hands of the erstwhile Starbuck — points for her performance, if nothing else.

7. Walt Cummings

It takes a little more than half this list before we start getting into the Mole Hall of Fame. There's no better transition into that sphere than through Walt Cummings (John Allen Nelson), the sniveling White House Chief of Staff who served President Logan at the end of season four and start of season five. Walt's secret affiliation with Russian terrorists was an incredibly exciting development at the time, finally giving viewers someone to blame for David Palmer's assassination. Of course, Walt was just the tip of the iceberg, obscuring the fact that the day's conspiracy was backed by none other than President Logan himself.

6. Kevin Carroll

You don't need to work at CTU in order to classify as a mole. Look no further than Kevin Carroll (Richard Burgi) for an example. In the first few hours of the series, this mercenary posed as doting father Alan York, a ruse designed to keep close tabs on Jack Bauer's wife, Teri (Leslie Hope). Kevin choking the life out of his supposed "daughter" was one of the show's first gut-wrenching plot twists, and still ranks as one of the best moments in the history of the series.

5. Jamey Farrell

The original mole! Sure, season one ended with a bigger bombshell, but this brilliant CTU programmer was the show's first-ever confirmed traitor. Jamey's reasons were more understandable than those of others, as terrorists threatened her family and forced her hand — not a far leap from Bauer's own circumstances during Day 1. Still, the revelation that Jamey was working with the wrong crowd was a big shock, if not quite as shocking as her subsequent suicide…and the subsequent reveal that it wasn't a suicide at all.

4. Marie Warner

After leaning hard on the mole horn throughout season one, 24 had its work cut out for itself in creating a compelling double-agent narrative for season two. Rather than introduce another spy within the CTU ranks, the show instead focused on an American family embroiled in suspected terrorist activities. Eagle-eyed viewers were able to piece the clues together before the show revealed that mild-mannered bride-to-be Marie Warner (Laura Harris) was secretly working against the Americans. It was a rewarding outcome for loyal fans, and a compelling twist punctuated by the startling image of the innocent Marie shooting her own fiance in cold blood.

3. Tony Almeida

It's heartbreaking to see Tony on this list at all, let alone this high up. Carlos Bernard's Day 1 veteran experienced more ups and downs than any other character in 24 lore save for Bauer. He betrayed his country in season three to save his wife, Michelle (Reiko Aylesworth), redeemed himself in season four, was killed off after trying to avenge Michelle's murder in season five, only to return from the dead in season seven as a villain. ("Return from the dead" makes it sound more dramatic than reality, but still, it's complicated.) Four episodes into the season, Tony revealed that he's actually still a good guy, secretly working with the terrorists to destroy them from within. Hours after that, Tony was decisively bad again, all in the name of vengeance for Michelle and their unborn son. That's the last note on which we left this formerly heroic character, but perhaps there's even more wiggle room for the morally flexible Agent Almeida when he returns in 24: Legacy.

2. Gael Ortega

Season three's opening episodes hinged on a risky premise: keeping the audience in the dark about Bauer's true motivations. Appearances to the contrary, Bauer was actually spending the first portion of the day's events trying to reestablish his cover with a Mexican crime syndicate, intentionally misleading CTU in the act. Bauer and Almeida were the key minds behind the plan, alongside trusted communications expert Gael Ortega (Jesse Borrego), a character viewers are at first meant to see as a traitorous mole. It's a huge subversion of the show's standard procedure, especially later in the season when Gael heroically gives his life in an attempt to save innocent civilians. Season three's big Bauer reveal is one of the coolest twists in 24 history, largely thanks to Gael, a character who proved that not all moles are created equal.

1. Nina Myers

There's no question about the top spot on this list. She was Bauer's former lover. She was his closest confidant. She was one of the decisive leads of the show. And then she was revealed in no uncertain terms as an unapologetic traitor. Myers (Sarah Clarke) is about as synonymous with 24 as anyone, the show's true face of villainy for its first three seasons. She killed Jack's wife and only lived so long to regret it, gunned down in cold blood toward the end of season three. While it was a mistake to kill Nina so early on in the show's run, there's no knocking the boldness of outing Nina as the mole at the end of season one, on such clear and decisive terms.

Which moles did we leave off our list? And how would you rank these characters? Follow our full 24: Legacy coverage at THR.com/24Legacy for interviews, news, analysis and more.