CSI: Crime Scene Investigation, or CSI: Las Vegas as I like to call it, hit a series milestone Wednesday night (Oct. 23) when its 300th episode aired on CBS. Now in its 14th season, the hit crime show premiered in 2000 and has seen countless murders, and a few series regulars leave, since.
For episode 300, titled "Frame by Frame," Marg Helgenberger made a guest return as Catherine Willows to help Sara Sidle and the other CSIs solve a 14-year-old cold case that has tormented them for years. Viewers were also treated to a little scavenger hunt, as the number "300" was used 14 times throughout the episode.
To celebrate this massive achievement, we've put together a list of CSI's top 10 guest stars.