Throughout its many, many incarnations, The Twilight Zone has dealt with almost every conceivable facet of the human experience. The show used science fiction, fantasy, and horror to explore themes as disparate as xenophobia, childhood, free will, consciousness, and, most consistently, the relationship between hubris and irony. It therefore comes as no surprise that Satan, a character that has preoccupied Western thinking for millennia, would eventually find a place in television’s fifth dimension.
What is rather surprising is the frequency with which The Devil appears, and how different he is between appearances. As you’ll see below, he can be anything from a horned, goateed guy in a tuxedo to a shifty gate guard to a she. Obviously, for a show as reliant on O. Henry endings as this one, spoilers abound.
The Howling Man (Robin Hughes), The Howling Man (1960)
The Devil almost never appears in his full, horn-and-pitchfork splendor on The Twilight Zone, but he does here, eventually. At first, he takes the form of a terrified prisoner, held captive by a company of monks. He screams constantly to be released, waiting for an unwary traveler to pass through and take pity on him. Upon his escape, he races through the monastery, revealing his true face as he goes. Unfortunately, the transformation goes a few stages too far, and by the end The Devil is so cartoonishly devilish that the effect is kind of ruined. Brother looks like Vincent Price dressed up as a ham logo.
Mr. Cadwallader (Thomas Gomez), Escape Clause (1959)

Interestingly enough, Cadwallader (who picked the name because it’s so much fun to say) is pretty forthcoming about his true identity. He’s The Devil, sure, but he’s also a businessman, and his business is seeking out folks to whom to offer complete immortality in exchange for their souls. And if they should happen to wind up with, say, a lifetime prison sentence, he’s even nice enough to dispense with all that immortality nonsense and claim their souls immediately.
Pip (Sebastian Cabot), A Nice Place To Visit (1960)
Pip’s a sweet guy, a white-suited Burl Ives type whose job it is to attend to the recently deceased soul of a small-time gangster. The afterlife is apparently like a luxury resort/casino, and Pip’s the concierge. He’s there to make sure that the guy’s every last whim is attended to, until gambling, carousing, and fun itself become drudgery. Eventually, the big reveal is that he’s been in Hell the entire time, with Pip putting him through the very worst sort of torment: monotony.
Nick (Dan Hedaya), Dealer’s Choice (1985)
https://youtu.be/d3N1ekU4LKI
Imagine the surprise of a neighborhood poker circle when they realize that their new friend, Nick, is an ageless Hell-dweller who has come to harvest their souls. Nick’s actually very nice, though, and despite his poker buddies knowing his secret, he really wants to finish their game. When he loses, he’s thankful enough for the diversion that he declines to damn any in attendance, and even uses his dark powers to restock the fridge. You catch more flies with honey, I guess?
Ms. Devlin, (Julie Newmar), Of Late I Think of Cliffordville (1963)

Ms. Devlin finds miserable old rich guys and allows them to to relive their own pasts. Interestingly enough, her marks are so evil that they don’t even have the abilities to sell their own souls, so she charges good, clean American cash for her services. And it’s hardly her problem if the past isn’t how you remember it, and when you return to the present you’re so broke that you have to become the janitor at the company you once owned.
I’m kind of in love with her.
Mr. Smith (Burgess Meredith), Printer’s Devil (1963)
Mr. Smith is a friendly, good-natured tempter with a crooked cigar (!) who predicates his entire strategy on the conceit that the very idea of The Devil is passé. He gets the protagonist to sign away his soul by taunting the hapless rube for being foolish enough to believe in archaic, medieval concepts like souls and devils. It’s likely the only time Satan has been depicted harvesting souls via peer pressure.
Unnamed Demon (Ron Glass), I of Newton (1985)
This guy is on call 24/7, waiting for frustrated mathematicians to accidentally summon him via arcane numerology. He’s gleefully aware of your standard soul-wagering tropes, as well as being wholly unapologetic about his evil nature. He’s also hip to current slang, really, really enjoys his work, and uses his limitless demonic power to manifest a series of constantly-changing t-shirt slogans. He is a treasure.
Incidentally, anyone want to make me a replica of the one that says “LET’S DO DAMNATION”?
“St. Peter” (Robert Foulk), The Hunt (1962)

As you can see, a lot of Twilight Zone Devils are involved in pretty low-stakes deception and temptation, but none so much as this guy. He sets up phony gates of Heaven and impersonates St. Peter to try to trick the soul of a hilljack to enter without his loyal dog, Rip. He says, contrary to what certain Don Bluth films might suggest, dogs aren’t allowed in Heaven. Only later do we learn that the dog-hating angel was Satan himself, intent on keeping Rip from catching a whiff of brimstone and alerting his master to the danger. The real Heaven is apparently just lousy with coon dogs.