Ten seasons of Friends means there are countless guest stars to choose from that have wandered their way into the main social circle, but one was extra impactful. So much so, even when they weren’t on-screen, their name could instantly send Chandler (Matthew Perry) into a jealous fit, delivering laughs from the studio audience. That is none other than Dr. Richard Burke (Tom Selleck), the “McDreamy” of ophthalmology, a special guest star who wasn’t supposed to be featured for as long as he did. But in his episodes, he gave insight into the various members of the friend group. There are questionable ideas behind his arc, but to the show’s credit, and with Selleck’s performance, he is part of the sitcom’s legacy despite appearing ten times in the show's 200-plus episodes.