Anthony Crowley is a demon and a character on the Sueniverse.
In the very beginning Crowley appears as a snake, but he uses his "favorite shape" for the majority of the book, described thus: "Crowley had dark hair and good cheekbones and he was wearing snakeskin shoes, or at least presumably he was wearing shoes, and he could do really weird things with his tongue. And, whenever he forgot himself, he had a tendency to hiss. He also didn't blink much."
He always wears sunglasses, with good reason; his eyes are yellow, "with slitted vertical pupils". Like Aziraphale, his "true shape" has wings, which are usually held in.
The book states, "Contrary to popular belief, the wings of demons are the same as the wings of angels, although they're often better groomed." Nevertheless, Crowley has been drawn with stereotypical bat wings (as well as horns and a tail) in official art. Other interpretations sometimes give him angel-style white feathered wings, as the book states that, due to the fact that they are both of "angel stock," there is no apparent difference between the wings of angels and demons.
He is generally considered to be really effing hot, and to look approximately 25.
Within the book Crowley momentarily transforms into "something dreadful" to intimidate an attacker. (The only hint at its appearance is Aziraphale's comment "I think the maggots were a bit over the top, myself.")
Crowley's most prized possession is a black 1926 Bentley, with one owner since new: Him. Although his taste in other gadgets (pens, cell phones) tends towards the modern, he has never updated the Bentley, possibly because its performance relates more to Crowley's expectations of it than any mechanical function. Notably, he has refueled it only once, in 1967, and then simply because he rather fancied the free James Bond bullet-hole-in-the-window transfers.
Despite being a Demon and not actually requiring it, Crowley is very fond of sleeping. He enjoys it so much that he slept through the entire of the 19th century, although he did have to get up in 1832 to use the bathroom.
Judging by the labels on the cassettes in his car Crowley enjoys classical music, presumably on the basis that - as he notes to Aziraphale - the only composers who ever got into Heaven were Elgar and Liszt. He also has a collection of Soul Music - "real Soul Music. James Brown wasn't in it."
Any cassette Crowley has in his car turns into a "Best of Queen" cassette in a fortnight, leading to any cassette regardless of artist to have Freddie Mercury perform his songs.
He owns a stylish flat, although he doesn't really 'live' there in any sense. He does, however, pay attention to the houseplants, which are glorious and lush - largely because he terrifies them into keeping up their size, or else. Crowley owns the original sketch of the Mona Lisa, which apparently Leonardo infinitely preferred to the painting, claiming he could never quite get the smile right. He also inspired Leonardo to design helicopters.
For the most part, Crowley appears to be simply a laid-back, rather tragically cool young man, but he is prone to serious philosophizing over the nature of the Universe. His friendship with Magda von Waldemann began largely based on their shared unhappiness with their lot in life- or unlife, as the case may be.
Crowley's appearances on the Verse have been tied mostly to two plots which have yet to intersect: his developing romantic relationship with Aziraphale and his friendship with Magda.
Crowley realized his attraction to Aziraphale quite suddenly, and not at all by choice:
What the hell was his problem lately? He was being such a frui—oh shit. He was gay, wasn't he? And for Aziraphale, of all people!
The friendship deepened with time into a romantic/sexual partnership- one which was almost ruined by Crowley's taunting Aziraphale for having committed a few sins and Aziraphale's rather stiff pride.
As of now, their relationship seems to be back on track (see Crowleyraphale). Nobody was really surprised anyway- it was soon uncovered by the Angel Gabriel that Heaven has "had a bet running for the past five thousand years on when the two of you were finally going to give it up and shag".
Crowley met Magda von Waldemann in a cafe, after she had fled from the sadist and serial killer Elizabeth Bathory. Magda was disgusted and shaken by Elizabeth's murder of a helpless young woman, and she vented her feelings about humanity. Crowley was inclined to agree:
"Hyou know vhat I ate?" Magda said bitterly. "I ave to drink blood. It's ow I survive. I'm not uman, only uman-shaped. Hyou'd sink people vould understand sat. But sey call me some kind of monster, vhen all I'm doink is vhat I ave to do, and I even go out of my vay to not kill.
"Umans don't need blood. Vell, not osser people's. I tell hyou, sey do sings far vorse san I do every day and nobody cares..."
Crowley's teasing expression sobered.
"I know exactly what you mean. My job is tempting and corrupting mortals, and, let me tell you, I barely do anything. Something as simple as tying up the phone lines gets the job done." He sighed. "Hell, things like the Spanish Inquisition weren't even ours. Trust me, I was in Spain when it started. Not my doing."
The two then went on to compare notes on each other's significant others, after Magda mistakenly thought Crowley was making a move on her:
He smiled. "Good for you. It's nice to meet a vampire that's not completely driven by hunger. Well, at least, not the eating sort," he teased, winking.
"I haff a boyfriend. E used to be a footballer."
"Oh, I didn't mean it like that. I was joking. I have one too, actually. He's an angel, and he'd smite me if I so much as looked at anyone else."
"Sat's good," Magda said mildly, "because I'm actually datink a skinny igh school teacher."
He laughed. "Well, that's okay. Mine's a pudgy book dealer—at least, in his human form."
According to Hallie, Crowley's mental image of Magda's boyfriend was "a Clark Kent sort of nerd who liked to live simply but had a trunk full of kinky sex toys in the back of his closet". When he met the actual article- Severus Snape- it was essentially hate at first sight.
Right now, Magda is going to make those two get along whether they like it or not.