Eagle

Eagles (also called Altair or Geese) are somewhat common bird enemies in Castlevania. They first appeared in the original Castlevania game, where an unlimited supply of them would fly in a straight line across the screen, drop Hunchbacks onto the ground, and then continue on their way. This type of Eagle also appeared in Vampire Killer and Castlevania Chronicles. It was later replaced by other flying creatures that dropped other types of hoppers, such as the Harpy, which dropped Gremlins/Ghoul Rabbits, and large Bats that dropped Flea Men.

Eagles have also been seen behaving similarly to a Raven. In Castlevania: Simon's Quest, it essentially a larger version of the Raven that hunted outside of towns rather than inside of them. In Castlevania: The Adventure, the Raven-like bird is called an Eagle in North America, but a Death Bird in Japan.

In newer games, starting with Castlevania: Symphony of the Night, Eagles are usually seen mounted by Flea Men.

Castlevania : Order of Eccelsia
It appears in Oblivion Ridge and Tristis Pass. It just comes from the top-right or top-left of the screen, and dash on you. Sometimes, it brings a Fleaman with it, which fall on the ground and act as a normal Fleaman. It's a neverending-spawning monster. If it misses you while dashing, it will just go out the screen.

Quest
A villager needs a feather of Altair to write his score. Kill the Altairs until they drop a Feather.