- Natalie Rhodes is the actress selected to play Nikki Heat. Changes her appearance to mimic Beckett and tries to spend a night in researching Rook (Castle)
- Duke Jones, PI that does "background" checks on potential clients, set up "honey trapping" operation and his alibi is that he was "banging" the neighbor lady
- Charles "Chuck" Russel - street magician who disapeared in front of Beckett when she wanted to question him ... "Alakazam Jackass"
- Tobais Strange: Hottest magician in town (in more ways than one!)
- John Ragland in 1999 was the officer working Johanna Beckett's murder case. In 1992 he started down a path that eventually lead to his covering up the real reason for her murder. He was murdered in front of Kate Beckett and Rick Castle in a diner.
- Gary McCallister is a retired cop, friend of John Ragland, "involved" in the cover up (and maybe more) of the murder of Johanna Beckett.
- Vulcan Simmons controls half of the drug trade in New York, never convicted. He provoked Beckett and she almost threw him through the one way mirror in the interrogation room.
- Reginald Easley Mr. Hixton's servant ...er correction by Mr. Easley, he is a Traditional English Butler ... apprenticed at Buckingham Palace. The Butler did NOT do it.
- Greg and Ty Page: the rapping ("Move that ass, Get on the floor") bank robbers from Florida, grew up with Jay Hixton and came to New York to help him with a drug pusher - to keep the pusher away from Jay's daughter.
- "Todd Shipley" The Blue Face Man, maintenance worker at an apartment building, found a money bag and he picked it up at the wrong time and the die pack went off covering his hands and face.
- Blanca "the mail lady" calls Castle "that crazy man" (in Spanish) and Esposito agrees with her. She alibied out Damian Westlake for his wife's murder.
- Morris Hasberg is a Russian carpenter, Beckett imitates his speech patterns / accent during interrogation.
- Omar Lincoln is a "tagger" while in interrogation says that he would have killed the woman just to shut her up.
- Mark Fallon of the Department of Homeland Security. He takes over the case of the dirty bomb and continued the role in Countdown. Known around the precinct as "Captain Douche Bag, DHS" (but no one called him that). He has to be hard nosed because of his job.
- Fariq Yusef is a very suave and polite member of the Syrian consulate and is in their secret police. Was first seen in Setup.