Angryverse/Zeta (AB 2)

Zeta (fresh from the hit movie) is an Eagle who is enemies with the Birds, but she works the Pigs even though the Birds and the Pigs are working together to stop her...

Logic makes no sense, Thanks Rovio!

When the EggSpark crash landed on Piggy Island, the radiation also hit Eagle Island, that transformed Zeta into the reformed Nightbird and the treacherous Slipstream!

Angry Birds 2
Zeta appears in Angry Birds 2 as a boss in a special The Angry Birds Movie 2 Event, by replacing any type of boss, like King Pig and Chef Pig. But for some reason, the enemies are still the pigs even through in the film, they are against Zeta and is helping the birds in defeating her.

But, despite her replacing every single boss in the game, she steals the Eggs for no apparent reason.

Angry Birds POP!
Zeta appears in Angry Birds POP! with a new Toons design, different from Angry Birds 2's design, you lazy butts. She is a playable character in which she has the Freeze Pop, which freezes a line of bubbles upon contact. She was first introduced in The Angry Birds Movie 2 event that also happened during the Zeta's Lair event, which replaced King Pig's castle, with the same gameplay of beating all five levels without losing a life.

Angry Birds Blast!
Zeta appears in a Treasure Hunt Excavation image and gave rewards to the player on the Monday before the launch.

Angry Birds Friends
Zeta appears in the Operation: Eagle Island as a boss. She has a new appearance based more on her movie design, different from the other designs.

She is a hard to defeat boss like the other bosses, but she doesn't need to be defeated in order to complete the level, she appears in all of the levels, often with Baby, seals, piranhas and Guard pigs. She screams when defeated, her voice and behavior are similar to Gale.

She always stays still, like the newer bosses that use a single sprite

Angry Birds Transformers
Voice Actor: Heljä Heikkinen (Archive Audio)

As Nightbird
Zeta/Nightbird plays somewhat similarly to Matilda/Nautica; she launches a series of large Ice Blocks in an arc at her targets, which explode with incredible smashing power, obliterating block towers with ease. However, despite their effects on the local (shoddy) construction, they don't do a whole lot to Walking Mortar Towers.
 * Squad: Specialists
 * Mission Type: ???
 * Unlock Type: ???



As Slipstream
Slipstream is a forthcoming character who will likely be added in the next few weeks. As usual, the game already teases her by sometimes enabling the player to choose her as a buddy.
 * Squad: Noughties
 * Mission Type: ???
 * Unlock Type: ???

As for her weapon: just a bunch of explosive ice blocks again.

Angry Birds Reloaded
Zeta in Angry Birds Reloaded is the main antagonist and boss of the game, but only in the Eagle Island section of the game. Outside of that, her sprite is just the Angry Birds Friends design just carried over into the game.

Angry Birds Transformers

 * Zeta uses the same upper beak model as the Grimlocks.
 * On top of that, she uses the same voice clips as Stella, instead of a more accurate voice for her
 * The explosive ice blocks are a reference to her using them as her main weapons in The Angry Birds Movie 2
 * For some reason, the game has two different body-types for Zeta as Nightbird, as one of them looks like the cartoon model, while the other one (pictured) is using the same torso as the Minion Pig Seekers.
 * Rovio has later confirmed on Facebook that it is actually a glitch that occurs after upgrading Nightbird to Level 15, but they’re working on it.