Angel was supposed to be a one-time character until David Boreanaz was found.

Boreanaz said that when he auditioned for the role of Angel, the role was described to him: "He may get hit, but he'll always come back. He has the grace and movements of a boxer, and he's mysterious".

In the Angel season three episode "Carpe Noctem", in which Angel was victim of a bodyswitch with an old man seeking younger bodies, he was played by Rance Howard.

Angel was born in Ireland, and in flashbacks his Irish accent is extremely strong. This accent disappears in the episodes set in this time, as one would expect, he having not been in Ireland for decades. However, it has been noticed that often when he says "Spike", the Irish accent comes back, turning it into "Spoike". It is unknown whether this is accidental or cunning acting.

Angel has a tattoo on his shoulder-blade of a griffin from The Book of Kells, with the addition of the letter 'A' beneath it. It is interesting to note that for the letter 'A' to represent Angelus, he had to have gotten the tatoo after becoming a Vampire. It's location on his back unfortunately means he has never actually seen it.

The first time it was planned that Angel would lose his soul, Joss Whedon was doubtful of David Boreanaz being capable of portraying the cruelty of Angelus. Joss changed his mind after he saw David performing Angelus and said that he never saw anyone creeping him out like that.

Also, Angel seems to be a "Fanilow" (a fan of Barry Manilow), particularly loving the song "Mandy". As he quotes, "I think it's kinda pretty". During his mental battle with Angelus, his demon stated that he particularly hated Angel's visits to Manilow's concerts. He also stated in Season 5 that he enjoyed William the Bloody's poetry, to which Spike retorts, "You like Barry Manilow."

Angel has appeared in by far the most episodes in Buffyverse, for a total of 166 episodes. Buffy and Willow are next, with 146 and 147 episodes respectively. He has also appeared in the most seasons of Buffyverse (all seasons of Buffy and Angel except for Buffy season 6) for a total of 11. He is also the only actor to appear in the premieres and finales of both Buffy and Angel.

Angel is a fan of ice hockey (he watches the game in "Life of the Party") and he hoped Connor would grow up playing ice hockey, one of the reasons being that it is a sport where most games are played indoors, and at night (allowing for vampires to spectate).

According to Cordelia Chase, Angel has a "thing" for petite blondes. She most likely drew this conclusion from his romantic relationships with Buffy Summers and Darla.

Angel makes something very clear: "There are three things I don't do: tan, date, and sing in public" (although he has broken all of those rules on occasion, such as when he sang in Caritas and later dated Nina. In season 1 Angel received the Ring of Amara which allowed Angel to go to the beach during the day, and in the entirety of season 5, Angel had access to necro-tempered glass).

The poet Baudelaire supposedly wrote the poem Le Vampyre about Angelus ("She")

Angel's turned into Angelus 4 times: First when he was sired by Darla, then when he made love to Buffy, then when he was fed a 'happy pill' [the effects wore off], and finally when the gang decided having his soul extracted was the only way to get information.