Giant Drill-Beaked Bird

This summon is a large bird which has a number of body piercings and the Rinnegan, implying that it is being controlled by Pain.

Appearance
The bird itself is unusual, as not only does it demonstrate a prominent and jagged beak, but it also features three distinct legs as well as wings. In the anime, however, it only has two wings.

Abilities
This summon can move at an incredibly fast speed, and can use that velocity combined with its beak to form powerful dive attacks. In the anime, the bird had additional abilities where it could lay a large quantity of eggs that subsequently explode like bombs, and while flying low over Konoha produced dust clouds strewn with lightning in its wake.

Itachi Pursuit Arc
It is summoned briefly during Pain's fight with Jiraiya.

Invasion of Pain Arc
He is summoned again to attack Naruto after he uses his perfected Rasenshuriken.

Shinobi World War Arc
The bird was next summoned by the reincarnated Nagato alongside the Giant Multi-Headed Dog to provide a way for Nagato to move. Itachi soon retreats atop of the bird's head alongside Nagato. Later, after Itachi is freed from Kabuto's control, he used Amaterasu on both Nagato and the giant bird, incapacitating it and its summoner.

Trivia

 * This summon's three legs make it reminiscent of Yatagarasu, the three-legged crow of Amaterasu, the Shintō goddess of the sun. Ironically it was defeated by Itachi's Amaterasu technique.
 * In its first appearance it was depicted with three legs and two wings. Later, after being summoned by the reincarnated Nagato, it was depicted with four legs and four wings.