In a city overpopulated by demons, warlocks and some really nasty lawyers, a creature of the night becomes Los Angeles greatest hope. Once a vicious vampire who terrorised Europe, vampire-with-a-soul Angel (David Boreanaz) helps the helpless in order to get his reward from the Powers that Be - to be forgotten, and regain his humanity. In his quest, he sets up Angel Investigations, with the help of an unlikely (and quite effective) evil-fighting team: wannabe actress Cordelia Chase, bookish Brit Wesley Wyndham-Price and street fighter Charles Gunn.

David Boreanaz – Angel/Angelus

Charisma Carpenter – Cordelia Chase

Glenn Quinn – Allen Francis Doyle

Alexis Denisof – Wesley Wyndam-Pryce

J. August Richards – Charles Gunn

Amy Acker – Winifred Burkle/Illyria

Vincent Kartheiser – Connor

Andy Hallett – Lorne

James Marsters – Spike

Mercedes McNab – Harmony Kendall

Stephanie Romanov – Lilah Morgan

Christian Kane – Lindsey McDonald

Julie Benz – Darla

Elisabeth Rohm – Kate Lockley

Daniel Dae Kim – Gavin Park

 In the episode "Epiphany", Lindsey McDonald is shown driving an old pick-up truck with an Oklahoma license plate. In real life actor Christian Kane who plays Lindsey drove to Hollywood, CA in an old pick-up truck from his home in Oklahoma. When the character of Lindsey left the show, he drove away in this same truck.

In the episode "Fredless", when talking about the Aliens series, a character says, "He's always had a thing for those 'Aliens' movies. Except for that last one they made - I think he dozed off." Series creator Joss Whedon wrote the script for Alien: Resurrection, although it was heavily rewritten.

Christian Kane (Lindsey) originally auditioned for the role of Riley Finn on Buffy the Vampire Slayer. Show creator Joss Whedon liked Kane so much that he asked him to play the character of Lindsey instead.

The character "Gunn" was named after with the brothers James Gunn and 'Sean Gunn' with whom Joss Whedon had worked previously.

It was originally intended for Angel's sidekick to be Whistler (Max Perlich) who appeared in two episodes of Buffy the Vampire Slayer. But when the actor couldn't commit to a series, the character of Doyle was created.

Each episode has quick flashes of images between most scenes. In the episode "Epiphany", for instance, between the scene with Angel and Darla and the scene where Angel goes to save Kate, there is a quick flash of a crew member holding a slate marker.

In "Spin the Bottle," the gang's memory reverts back to before any of them met. Cordelia, seeing Angel for the first time, says "Hello, salty goodness." She said the same line the first time she saw him on Buffy the Vampire Slayer.

Andy Hallett holds the record for the actor who took the longest to become a regular. He guest starred in over 40 episodes during the second, third, and fourth seasons before finally being added to the main opening credits of the 14th episode in the fourth season.

The address for Angel Investigations at the old hotel is: 1481 Hyperion Ave, Los Angeles, CA 90026. Phone (213) 555-0162. Fax (213) 555-0163.

The songs that are sung to Lorne by Lindsey in "Dead End" and by one of his clients in "Sleep Tight" were both written by co-creator and executive producer David Greenwalt, as was the title theme to Cordy's sitcom in the fantasy sequences in the episode "Birthday". That song was sung by both Greenwalt and consulting producer Marti Noxon, who also appears in the sequence.

Three of the show's writers have appeared in cameo appearances in the show. Joss Whedon played Lorne's brother Numfar in "Through The Looking Glass" (he dances in the background), David Fury played a devil worshipper who is threatened by Angel in "Reprise," and a puppeteer in "Smile Time" and Marti Noxon plays Cordelia's friend in the faux-credit sequence to the sitcom Cordy in the episode "Birthday".

The WB's announcement that it was canceling the show came at a time when it was rated second only to "Smallville" among 18-to-34-year-olds. Earlier in the same month, WB's weekly ratings release revealed that "Angel" had earned "outstanding year-to-year gains" among demographic groups.

In the series finale, Charles Gunn uses a pair of retractable stakes, hidden in his sleaves, while fighting the senatorial candidate's cronies. These are exactly like the ones used by Angel in the series' first episode.

After being listed as a guest star on both this show and Buffy the Vampire Slayer for the previous seven years, Mercedes McNab was finally added to the opening credits of Angel for the final 6 episodes.

In "The Cautionary Tale of Numero Cinco" there is a flashback where one of the brothers answers the phone. What he says in Spanish translates to: "What? The devil built a robot?" Numero Cinco mentioned the incident with the Devil's Robot to Angel earlier in the episode.

In the Season 4 episode "Spin the Bottle", Wesley mentions a test where a powerless slayer is locked in a house with a rabid vampire. This is a reference to the Buffy the Vampire Slayer episode "Helpless" in Season 3.

In the episode "Waiting in the Wings", Joss Whedon had imagined a scene in the dressing room, where a mirror showing Cordelia and Angel standing behind her would be seen. Ross Berryman had to remind him that Angel was a vampire and could not have a reflection.

As of the series finale, David Boreanaz is the only actor to have appeared in every episode, David Boreanaz and Christian Kane are the only actors to appear in both the first and last episodes of the series and David Boreanaz, Charisma Carpenter, Alexis Denisof, Julie Benz and J. August Richards are the only actors to have appeared in every season.

Barry Manilows "Mandy" makes a few appearances in the series. Angel sings the song in "Judgement" (2-1) and the end credits roll over that as well. In "Orpheus" (4-15), we see Angel play the song on a jukebox in one of his flashbacks. In "The Magic Bullet" (4-19), Angel and Connor sing the song, replacing "Mandy" with "Jasmine".

In the opening credit sequence of every episode, there is an image of a woman standing by the side of a street. This is not actually taken from any episode in the series but rather it's from the Buffy the Vampire Slayer episode "Anne", though the scene takes place in the show's setting of L.A.

Sarah Michelle Gellar turned down the offer to appear in two Season 5 episodes, opting to star in The Grudge instead.

Anachronism: In "Have You Now Or Ever Been...", a flashback to 1952 shows a woman who embezzled $11,000. When the money is shown, it is in the new $100 bill that wasn't issued until 1996.

Revealing mistake: In the first episode of the second season, as the gang is walking through a gym, you first see them in a mirror walking across the floor. Angel is not walking with them, but to the right of the screen at the edge of the mirrors you can see him waiting for the group to catch up to him. He starts walking to fall in line with them as the edge of the mirrors are reached and the camera pans onto the fang gang.

Continuity error: In "The Ring", Angel gets shot and stabbed but during the final fight the wounds change sides in every shot.

Revealing mistake: A goof seen in the first episode ("City of") that appears in the opening credits of every episode is when Angel is walking down an alley. In a puddle of water you can see his reflection.

Crew or equipment visible: In Episode 5.17 "Underneath", in the Wolfram & Hart mystical holding dimension, when Lindsey's hand reaches for the basement doorknob, the crew and the rest of the studio are reflected in the doorknob.

Continuity error: In "Birthday" Angel (possessed by Cordelia) writes an address on a wall. The address is gone in the next shot when he's blown backward.

Continuity error: In the episode "Eternity" Cordelia flings water from a sports bottle on Angel. In the next shot the water level in the bottle is unchanged.

Continuity error: In "Time Bomb" Illyrea shoves Wesley and his desk against a window and the blinds are closed. In the next shot as she leaves his office the blinds are open.

Continuity error: In "Loyalty", Lilah holds up a pad of paper with the words "COUNT ME IN" written on it. The camera cuts away, then cuts back to her, and the sign she is holding is written differently.

Revealing mistake: In "Rm w/a Vu", Cordelia stays with Angel when her apartment is infested with cockroaches. After she showers, she is combing through her hair with her fingers looking in a coffee pot (because Angel doesn't have any mirrors). She sets the pot back down on the table and Angel walks past, you can see his reflection on the coffee pot.

Continuity error: In "Double or Nothing", Angel and a demon gambler both cut a card from the deck. The gambler cuts first, his card a 9 in close-up shots. In the long shots of the table, though, his card becomes a 5.

In the end credits for "She" the end credits play over footage of Angel and Wesley dancing at Cordelia's party, complete with dance music.

The end credits for "Judgement" roll over footage of Angel singing karaoke at Lorne's bar.

Two deleted scenes appear on the Season 3 DVDs. The first is a segment from Cordelia's fantasy sitcom 'Cordy' from the episode 'Birthday' and the second is a hilarous sequence where Wesley has a fantasy about Fred and himself doing ballet from the episode 'Waiting In The Wings'

The R1 and R2-UK DVDs of season 2 are presented in widescreen (16:9), whereas the television broadcasts were not. They show an open matte image, which shows more on the left and the right side but sometimes even show crewmembers or other things that were not meant to be seen. They 4:3 framing is the one intended to be seen.