In 1966, the popular British television series, The Avengers, aired an episode titled "A Touch of Brimstone." The episode featured what was basically a modern-day version of the Hellfire Club (an exclusive British club from the 18th century that was rumored to engage in all sorts of crazy debachaury and orgiastic rituals), and during the investigation, Emma Peel was drugged and forced into dressing up as the Queen of Sin.
As you can tell from the photo, the episode was quite racy for the time, and the episode had to be edited to appear on British television, and was barred from America television at the time.
Well, when Chris Claremont and John Byrne were writing the X-Men together, and coming up with ways of "darkening" Phoenix, they decided to introduce the Hellfire Club, and used that episode of the Avengers as inspiration (Emma Peel being forced into dressing up as the Queen of Sin is quite similar to Jean Grey being "forced" by Mastermind into becoming the Black Queen).
Here's Byrne on the topic, from his forum,
I first encountered Peter Wyngarde, as an actor, on the Avengers episode "A Touch of Brimstone", which dealt with Steed and Emma having an encounter with the Hellfire Club. Later he turned up on a British series called Department S, and its spin-off Jason King (the name of his character). When Chris Claremont decided he wanted to do a Hellfire club arc in UNCANNY X-MEN (he had just seen the above mentioned Avengers episode) as part of the "darkening" of Phoenix, I suggested the "in-joke" of having Mastermind, in his disguised form, resemble Peter Wyngarde and, mixing character and actor, that his name be Jason Wyngarde. (Chris seemed to have some small problem remembering if this was supposed to be Mastermind's real name, or one MM had made up. It is refered to both ways in the story arc.)
Here is Jason Wyngarde from the comic matched with Peter Wyngarde as Jason King, the Department S spin-off (and, remember, Wyngarde also appeared in the initial A Touch of Brimstone episode, as the villain).
Since he was already using a real actor for the inspiration of ONE of the Hellfire Club member, Byrne decided to use real actors for the other Hellfire members (and, in addition, Emma Frost likely got her first name from Emma Peel).
Sebastian Shaw = Robert Shaw
Donald Pierce = Donald Sutherland (and the last name Pierce, from Sutherland's turn as Hawkeye Pierce in M*A*S*H)
Orson Welles = Harry Leland (Harry from Welles' turn as Harry Lime, and Leland from the character Jed Leland in Welles' classic Citizen Kane)