An immortal sorceress and fortune teller who served as Merlin's apprentice thousands of years ago (see Demon Knights for more of that). She assembles the team to handle the threats that the regular Justice League can't.
Junkie Prophet: An interesting subversion. She can indeed see the future, but it's what she sees that causes her to take drugs (whether they're of an illicit or medical nature is unsure).
The Leader: Arguable. She assembles the team, but seems to trade off the role with John and Zatanna.
Prophecy Twist: In the Books of Magic Arc, she predicted that the group would leave Tim Hunter behind on a parallel world. They do, but only because Tim chooses to stay and learn how to use his magic in a place better equipped to handle his powers. His father also stays with him.
In life, Boston Brand was an acrobat, and a massive jerk... until he was shot during his act one night. As the ghost Deadman, he seeks to do good in the world as penance for his behavior in life.
All Men Are Perverts: Tries to get Dove to engage in a lesbian kiss with June Moone while he's in control of the latter's body. It's implied that this wasn't Boston's fault, but a result of the Enchantress's madness affecting his personality.
John admits, while sober and not magically-compelled, that he feels responsible for the death of Zatanna's father and it will not do him any favors winning Zatanna's heart back.
He has either forgotten how good he used to be, or thinks that he is beyond saving. He remarks that he could never be as kind as Zatanna, but in flashbacks he wasn't far off from her in terms of decency.
The Leader: Arguably. He's often the most effective member of the group, so he winds up taking charge a lot of the time—usually in a way that makes everyone hate him.
Manipulative Bastard: In general, but by far the worst example is how he gets Zatanna and the others to come along with him on the mission against Felix Faust.
Morality Chain: John saves Zatanna's life several times and clearly worries when she is in danger. Not that it stops him from using Zatanna in part of his own schemes. Or from flirting with Black Orchid right after he told her about his feelings for Zatanna. Or from killing Zatanna in a possible future, according to Xanadu. John really does not like the last one.
Screw Destiny: After Xanadu prophesied that John would kill Zatanna in the conclusion of the Books of Magic arc, the House of Mystery is stolen. John does not call Zatanna to help despite her usefulness, which is likely an attempt at this trope.
Right before that, John's intended loss on a horse race may have been another attempt to change destiny—which was rejected.
Sympathetic Magic: Oh, the irony. He tends to use blood, hair, and other personal objects in spells, which makes this his specialty.
Too Spicy for Yog Sothoth: Deadman attempted to possess John and left a few moments later, calling John filthy and disgusting.
Used to Be a Sweet Kid: As a young man, he was more of a Loveable Rogue who fell in love with Zatanna at first sight, then saved Nick out of pure decency. While not a villain in the current series, he's still extremely jaded and cynical to the point where Zatanna would not put it past him to kill an innocent child for selfish reasons.
A shapeshifting agent of A.R.G.U.S., the government's superhuman-response agency. She is the only non-magical member of the team. Supposedly.
Shade the Changing Man possesses the magical M-Vest, which allows him to manipulate the world around him.
The daughter of Giovanni Zatara, one of the world's greatest magicians, and a proficient magician herself. Can make anything she wants happen by saying words backwards. Unless something is messing up her spells.
Beware the Nice Ones: On Epoch, where everyone's natures are reversed, Zatanna appears to be unchanged... until she nearly kills someone, and the only remorse she shows is at Timothy's distress. She also mentions that she doesn't trust people claiming Timothy is their "Chosen One", because that would be the first thing she'd say to manipulate a lonely child. Basically, she and John switch personalities.
The Heart / The Leader: Being the most well-adjusted member of the group, Zatanna tends to act as a buffer between John and the rest, and the others trust her most. She trades off the Leader role with Constantine and Xanadu.
Kill the Cutie: According to a prophecy from Xanadu, John will (might?) kill her.
Last Name Basis: She calls John by his last name until their relationship improves.
Nice Girl: She gets along with everyone because of this. Except John, who has a history with her. Although she even starts to patch things up with him. Tied with:
Plucky Girl: She's had a horrible life and tends to be the first one whose powers stop working, but remains the most compassionate member of the group.
Power Nullifier: For one reason or another, Zatanna's spells almost never work when it's important during the first few arcs.
Put on a Bus: When the House of Mystery is stolen in the Horror City arc, John does not call Zatanna in.
Stepford Smiler: In the first issue, Batman tells Zatanna that she is not stable, and most later references imply that she still hasn't gotten over watching her father burn to death because of John's actions.
Your Cheating Heart: Her relationship with Nick slowly withered as he obsessed over the Books of Magic, and she turned to John for comfort. Nick doesn't particularly care, which makes the situation uncomfortable but not outright bad. When he begs them for help, they go to save him out of guilt. However, it was a ploy for Nick to kill John and Zatanna, which makes them ultimately sympathetic.
The main hero of I, Vampire.
A powerful mystic working for A.R.G.U.S.
A witch driven mad, whose fractured psyche starts to tear apart the magical world as a result.