Balkiry

"A battle plane type bird robot last seen in "SKY CHASE ZONE" from "Sonic 2". A whole bunch of them can be shot out of Metal Sonic's weapon unit, "Metal Carrier", in Episode II."

- Profile, Sonic the Hedgehog 4: Episode II website

Balkiry (バルキーン) is a bird-like plane Badnik created by Dr. Eggman. Balkiry have made their first appearance in Sonic the Hedgehog 2. These Badniks attack with the straight line or follow their target either at medium or high speeds like a homing missile.

Appearance
Balkiry Badnik's design is a hybrid of a bird and plane. The red and grey metallic body have wings on each side, a vertical stabilizer and two rotors on its back, which makes the Badnik move on medium or high speed. The head has small eyes facing front and a yellow bird beak. They have two support legs with small wheels that resemble eagles' feet.

Balkiry's appearance in Sonic the Hedgehog 4 is more detailed, as now the support feet are removed and it has received two extra wings in the vertical stabilizer. From Sonic Lost World though, Balkiry once again retains its cartoony design from previous games.

Powers and abilities
These Badniks have been given a simple pattern, as they fly and attack toward its target like a missile. The flying speed of Balkiry varies on certain models, as some of hover with medium speed, while others fly with high speed. In Sonic Pocket Adventure, these Badniks are also able to move to lateral directions, following its moving target.

In Sonic the Hedgehog 4: Episode II, Balkiry can be launched from the Metal Carrier. In Sonic Lost World for Nintendo 3DS, these Badniks are able to do swing around in the mid-air to change their charging direction.

Sonic the Hedgehog 2
The Balkiries first appeared in Sonic the Hedgehog 2 as exclusive enemies in Sky Chase Zone. In this game, they fly fast in the opposite direction of the Tornado, which is the only solid object the player can stand during the Zone. At the beginning of the Zone, the Balkiry appears one at a time, but as the Zone progresses, they appear in larger groups of two or three, and at much faster speeds. They are not particularly dangerous, although some of them tend to move quickly and can take the player by surprise.

Sonic Pocket Adventure
In Sonic the Hedgehog Pocket Adventure, the Balkiries are featured again in Sky Chase Zone along with other Badniks from previous games. The Balkiries have similar attack patterns as in Sonic the Hedgehog 2, except they are now able to move in lateral directions, enabling them to follow the player should they dodge them.

Sonic the Hedgehog 4: Episode II
In Sonic the Hedgehog 4: Episode II, the Balkiries are featured in the first act and boss fight of Sky Fortress Zone. In this game, the Balkiry's design and its behavior is slightly different from Sonic the Hedgehog 2; they are now launched from the Metal Carrier and cascade down on the player from the top of the screen. However in the Boss Act, some Balkiries behave just as they did in Sonic the Hedgehog 2.

Sonic Lost World
Balkiries later reappeared in both the Wii U and Nintendo 3DS version of Sonic Lost World. During the game, all Dr. Eggman's Badniks, the Balkiries included, got hijacked by the Deadly Six.

In the Wii U version of the game, the Balkiries appear as obstacles flying by in the skydiving sections of Desert Ruins Zone 2. In Tropical Coast Zone ? and Sky Road Zone 3 however, they charge from the right in string formations towards Sonic when he is maneuvered through the air, though the player can destroy them from above by performing Spin Attack. Balkiries also appear in Hidden World Zone 2, where the player can only avoid them while piloting the Tornado.

In the Nintendo 3DS version of the game, Balkiries appear in Sky Road Zone 1 and 2. In Zone 1, they will charge forward until they come across the ceiling, wall or corner where they will turn around and head in the other direction. Here, the player has to destroy them to unlock a switch in a case. In Zone 3 though, Balkiries will fly towards Sonic in different string formations, which the player can only avoid while controlling Sonic on the rocket.

Sonic Runners
In Sonic Runners, Balkiries are one of the most common Badniks in the flying type character's stages. Like in previous games, they charge from the right direction, and appear separately or in groups.

Balkiry in Sonic Runners come in three types. Aside from the regular types, there is golden Balkiries that give 300 extra points each when destroyed, and black ones called Super Balkiry that only Color Powers and power type characters can destroy. Any type of Balkiry contains Animals inside them.

Sonic the Comic
Balkiry Badniks have made frequent appearances in Fleetway's Sonic the Comic, where these Badniks are standard flying units of Doctor Ivo Robotnik's Badnik army. These Badniks are first seen in issue 15's cover. Balkiry's model is seen at background in story "Sonic the Human!" of issue 17. Buzzer and Balkiry Badniks got launched from the convention tower of Chemical Plant Zone after Sonic and the Freedom Fighters are discovered from the crowd. All civilians believed this scene being part of the show. They soon change their mind when Balkiry Badniks start dive-bombing them. Despite the strike, Sonic and Freedom Fighters manage to destroy the convention tower and the Badniks along with it by pushing the Robotnik statue to the tower.

Robotnik launches one Balkiry Badnik after Shortfuse the Cybernik once relentlessly tailed one in order to destroy it, but was destroyed by Knuckles the Echidna. Another set of Balkiry Badniks are got down this time by Shortfuse the Cybernik himself and Tekno in Chemical Plant Zone. Later, Balkiry Badnik is then seen kidnapping Amy Rose, as this makes prompting the other Freedom Fighters to realize how badly they needed Sonic. Balkiry Badniks are also seen along with other Badniks ordered to attack by Grimer. After the fall of Robotnik's empire, later models of Balkiry Badniks were shown to be built with an electric attack, one of which accidentally revived Kog from under Citadel Robotnik. Balkiry is also seen during the surprise attack of Badniks, where they later reveal to be sent out by Agent X.

Trivia

 * In Sonic the Hedgehog 2, Balkiry has unused in-game sprite showing its landing pose, that can be found in the game's coding. It is possible that they were originally intended to start flying from this pose at Wing Fortress Zone, but the movement has then become unused for unknown reasons.
 * In Sonic X, a robot called E-11 Beacon is based on Balkiry though it has a purple-colored scheme.