The Best Celebrity Unsubs According To Criminal Minds Fans

The heart of "Criminal Minds" may be the members of the BAU — the agents who fans have grown attached to — but the show is nothing without its villains.

The "unidentified subjects" (unsubs) throughout the run of "Criminal Minds" are as creepy and haunting as the main characters are lovable and amusing. Despite appearing in only a few episodes, or even only one, some unsubs make their mark on the series, living long in the fandom's collective memory. 

Unsubs can be memorable for their interactions with the main cast, or for a particularly gruesome MO, or for a complex and compelling episode, but it certainly helps when the unsub is played by a familiar face. A few of the best are guest roles by well known actors, who've gained fame through other movies and shows, and who often get more than just a one-off episode.

In 2021, Reddit user MandaPandaLee asked the "Criminal Minds" fans of r/criminalminds which antagonist played by a celebrity actor is their favorite. They received plenty of responses, and here's who fans gave the most love.

One of the most popular celebrity unsubs is Aubrey Plaza, who plays the conniving hit woman Cat Adams in four episodes, including one of the series' best rated, Season 11's "Entropy." Most audiences know Plaza from the sitcom "Parks and Recreation," on which she played April Ludgate, but on "Criminal Minds," she ditched the dry April for the dangerous Cat Adams, whose storylines mostly revolve around her relationship with the team's resident nerd, Spencer Reid (Matthew Gray Gubler). 

Despite Cat's controversy in the fandom — fans are split over her character arc — plenty of commenters picked her as one of the best celebrity unsubs. User tsp_of_dopamine commented, "She was freaking fabulous. The energy between her and MGG during their confrontations is palpable. And they're both just ... so hot."

Another fan favorite is James van der Beek, who's best known for playing Dawson on the teen drama "Dawson's Creek," but made a memorable villain in a two-part story arc in "Criminal Minds" Season 2. His character was Tobias Hankel, a serial killer suffering from having multiple personalities, who famously kidnaps, tortures, and drugs Spencer in "The Big Game" and "Revelations." User mccabebabe commended how he plays the three different characters in one body, saying, "Yeah, I actually felt bad for the Tobias personality (Dad and Raphael not so much). I think JvdB had one of the toughest jobs ever on CM, having to play three characters basically. He was so good, actually making it possible to hate one of him (dad) and feel sorry for another (Tobias)."

Over the seasons, "Criminal Minds" has had enough good celebrity guest unsubs that fans threw out several more recognizable names. C. Thomas Howell, who starred in "The Outsiders" as Ponyboy Curtis, has one of the longest villain arcs on "Criminal Minds" as the devastating killer called The Reaper, aka George Foyet. User Sirena_Seas called him "harrowing."

Another popular choice is Tim Curry's ("The Rocky Horror Picture Show," "Clue") haunting appearance as Billy Flynn, aka The Prince of Darkness, a serial murderer and rapist who strikes during blackouts in the season finale of Season 5 and opening episode of Season 6. User tsp_of_dopamine commented, "He made [my] skin crawl in his episodes, which was exactly the point." Another user, who has since deleted their account, said he was "so over the top but perfect for that story."

Plus there is Mark Hamill — yes, that's Luke Skywalker, himself — who played The Replicator, aka John Curtis, in the two-part Season 8 finale. All throughout the season, The Replicator haunts the BAU, watching them and killing victims by copying other unsubs' methods, until he attacks them and kills Section Chief Erin Strauss (Jayne Atkinson). User kdb21 said, about their favorite celebrity unsub, "Gotta be Mark Hamill i love star wars and he was a great villain."

Finally, some honorable mentions are "Beverly Hills, 90210" star Luke Perry in the episode "Minimal Loss," and "Malcolm in the Middle" star Frankie Muniz in the episode "True Night." Instead of seeming strangely out of place, each of these actors embodied their unsub spectacularly.