John Mayer had a guest starring role as himself in the CSI Season 7 premiere, "Built to Kill, Part 1." It was a lot like the Wallflowers role mentioned earlier. Cirque du Soleil also guest starred. If you can call it that.

Sean Young joined the lineup for the second half of the CSI Season 7 premiere as the mother of one of the suspects. She wasn't happy to learn her son was fingerprinted, at all!

Jim Beaver guest starred as a tourist who was happening by when he got the beat down in an alley on CSI Season 7 Episode 4. Greg was beaten, as well, as he got caught in the melee and saved the fellow.

David Ramsey plays Gerald Crowley in "Burn Out," CSI Season 7 Episode 6. Crowley is the father of one of two missing boys, one black and one white. He intitially thinks his father might be to blame.

On CSI Season 7 Episode 8 Frank Grillo guest starred as Gary Sinclair, the better half to Joanna Going's character, who played identical twins.

Yep, another two-fer. After all, Joanna Going and Frank Grillo were both in Kingdom in 2014 and both in the same episode of CSI in 2006. Worth mentioning, don't you think?!

I'm not sure Rober Daltrey's foray into television on CSI Season 7 Episode 9, "Living Legend," was as successful as Glen Frey years earlier on Miami Vice, but whatever.

On CSI Season 7 Episode 18 Walton Groggins WAS A MURDERER!!! Not of one, not of two, not even of three women. He got a whole gaggle of 'em as Marlon Frost. He received justice.

CSI Season 7 Episode 18 didn't see Laura Vandervoort being Bitten, but she was almost hit and smashed by a runaway limo. Hey, those things happened all the time in Vegas!

How freakin' adorable is Britt Robertson this young and as a brunette? Well, not much else about her story in CSI Season 8 Episode 3, "Go to Hell," is adorable. She's used an abused. It's terrible.

Octavia Spencer working at a fast food restaurant? I don't think so! But that's what she's doing on CSI Season 8 Episode 14 as Sherry.

Katey Sagal is playing a tempermental actress and her photo standin in CSI Season 8 Episode 16 and they BOTH manage to get murdered. Hahahahahaaaa!

Jeffrey Tambor guest starred as an artist who created some pretty freaky death-like sculptures that happened to take shape in the real world in CSI Season 9 Episode 3.

Not quite the Viking in CSI Season 9 Episode 10, as Maureen Martin Katheryn Winnick is a victim of the Dick and Jane Killer. Or she might be. Dun dun dun dunnnnnn!

Michael Cudlitz was A MURDERER on CSI Season 9 Episode 11. Don't ever let him tell you any differently!

When a dude falls to the ground after his parachute doesn't open, Charisma Carpenter's character, Mink, is one of the suspects in his maiming and possible death on CSI Season 9 Episode 19, "The Descent of Man."

Where did Liza Weil learn how to get away with murder? On CSI Season 9 Episode 20, of course, where she was a part of "A Space Oddity." Duh.

ET go home! Henry Thomas was a prisoner conspiring against another inmate on CSI Season 9 Episode 20, "If I Had a Hammer."

Arrow's Mama Smoak got into a speck of trouble by helping out that aforementioned inmate, Henry Thomas during CSI Season 9. Whoopsies!

Jason Dohring plays a suspect in his father's death in "Long Ball," CSI Season 10 Episode 12. He looks sad, but does that make him a murderer?

Everyone's a suspect when ... no, Matt Barr is whisking up some drugs in the hotel room as Bellermine Quisk on CSI Season 10 Episode 16, "The Panty Sniffer." With a name like that, what else could he do?

HOLY MOLY! Future Switched at Birth spouses Lucas Gabreel and Cassi Thomson starred as little squinterns on CSI Season 10 Episode 20! How friggin cute is that?!

Yep. It's little baby Bieber starring in the CSI Season 11 premiere. Remember when he was all sweet and innocent? Is he even a thing anymore?

Sasha Roiz tries to get a little close to Marg Helgenberger on CSI Season 11 Episode 2, "Pool Shark," but she shuts him down. Crazy lady.

Another Vampire Diaries representative as Annie Wersching plays Dr. Priscilla Prescott on CSI Seaosn 11 Episode 5, "House of Hoarding."

Can Josh Dallas save the day? We sure hope so! He's on the bomb squad on CSI Season 11 Episode 15, "Targets of Obsession." It's that damn Bieber again, raising trouble!

Matt Lauria as Agent Matthew Pratt and Grant Show as Agent Viggo McQuaid guest starred on CSI Seaosn 12 Episode 9 as a couple of unwanted FBI dudes interested in a specific weapon on a case. What they couldn't say really annoyed everyone.

Rose McIver as Bridget Byron was in a very tight space on CSI Season 12 Episode 13, "Tressed to Kill."

Mary Page Keller had a husband and son along with her on the suspects list on CSI Season 12 Episode 14. Not a fun place to be!

Here's something you don't see Quentin Lance do very often – SMILE! The jury's out on whether Paul Blackthorne should be smiling on CSI Season 12 Episode 17 as the college professor teaching...gossip...however.

Kyle Richards caught the acting bug just in time for the Halloween episode (Get it? She was in the original Halloween movie...) as a busy body neighbor on CSI Season 13 Episode 5.

When DB helped out his old pal Mac Taylor on CSI Season 13 Episode 13, it was Kirk Acevedo who turned out to be the baddie who Mac tossed around the interrogation room. Fun!

David Cassidy guest starred as a professional poker player and MURDER VICTIM on CSI Season 13 Episode 16, "Last Woman Standing." Certainly wasn't this man!

Poor Lucas Bryant guest starred as a murder suspect and reunion guest who never went anywhere, but almost got lucky the second time around on CSI Season 13 Episode 17, "Dead of the Class."

Neal McDonough made a big mistake holding a gun on one of their own! He was living off the grid on CSI Season 13 Episode 18 and a suspect in a murder.

Who doesn't like a good mud bath? So asks Dichen Lachman's character Jessica Lowell during CSI Season 13 Episode 20, "Fearless." Personally, I'm afraid of them.