As Criminal Minds approaches its final season, we're reflecting on some of its best moments, particularly its guest stars. The crime drama has had an impressive cast, both well-known actors and those who found fame later on. While some of the most famous guest stars arrived on set with a notable reputation, there are also performers who appeared on the show before they became household names. It's impossible to mention all the guest stars, but here are some of the most famous and memorable. Paul appeared in the show's first season as a goth teenager linked to the episode's apparent Satanic murders.

Lynch has made a few appearances as Diana Reid, Spencer's schizophrenic mother. Monaghan had a creepy role as a young serial killer before his success in Shameless and Gotham. Van Der Beek played a serial killer with a split personality, reuniting with his Dawson's Creek co-star Monroe. Muniz played a traumatized crime victim turned serial killer. Alexander's character started off as a professor but was revealed to be much more sinister. Young had an eight-episode arc as Beth Clemmons, connected to Hotchner after a tragedy. 

Trachtenberg played a stalker who killed Dr. Reid's girlfriend. Hamill played The Replicator, a serial killer taunting the BAU team. Savage played the younger version of an existing main character. Plaza portrayed a cold-blooded assassin plotting against Reid.