HBO’s forthcoming mockumentary “7 Days in Hell” is, essentially, a very long Funny or Die sketch in which Andy Samberg’s renegade tennis player Aaron Williams, long retired from the game, comes back for an epic matchup against his nemesis, the moronic but nearly unbeatable Charles Poole (Kit Harington).

In addition to the regular roster of comedians — Will Forte, Fred Armisen, Lena Dunham, Howie Mandel — director Jake Szymanski roped in a surprising number of cameos from actors, athletes and journalists not normally associated with satire, beginning with Harington, who’s best known for playing the über-serious (and controversially mortal) Jon Snow on “Game of Thrones.” Take a look below at some of the other familiar faces you’ll see on your TV screen come Saturday night:

The tennis superstar plays it straight as the sister of Aaron Williams, saying their father pulled a “reverse ‘Blind Side’ . . . My dad, he took a white kid and made him play tennis.”

The actress, who plays Charles Poole’s victory-obsessed mother, is better known for her dramatic roles, like Katherine Hale on “Justified.”

You may not recognize Gillan as Charles’ model ex-girlfriend; she was last seen with a bald head and blue body paint as a villain in 2014’s “Guardians of the Galaxy.”

The tennis legends play themselves as commentators on the Williams-Poole match: “It was nothing short of a miracle,” says the once famously foul-mouthed McEnroe.

The actor, who’s a repellent, beer-bellied sports-talk-show host in “7 Days,” has been known to dabble in comedy (remember his turn on “30 Rock”?) but was most recently seen brooding over Carey Mulligan in the Thomas Hardy drama “Far From the Madding Crowd.”

She appears as a bird-flipping Queen of England; you may remember her as Will Forte’s sharp-tongued mother in “Nebraska.”

The journalist plays herself as an interviewer of the astonishingly dumb Charles Poole, who mistakes her for Bryant Gumbel.

The magician turns up as an old drinking buddy of Aaron Williams’. The Las Vegas performer deftly sends up his own image as a dramatic master of the magical arts.