Microsoft's free-to-play brawler Killer Instinct is getting a new character next month in the form of Eagle. I guess you need to be familiar with the original because the teaser embedded above is very inside baseball. Aside from there being some kind of eagle featured (because the character is called Eagle) there's not much in the way of "information".
So let's defer to history (aka, the Killer Instinct Wikia). In the 1994 Nintendo 64 original, Eagle was "a gifted amateur fighter in his own right" and "skilled in both boxing and wrestling, compared to his mountain of an older brother who became a football star. Devoted in his training to become the ultimate fighter and protect the ones he loves, his skills earned him a spot with the underground spy ring the Disavowed, who later sent him to infiltrate the first Killer Instinct tournament."
So he's not an actual eagle, in other words. The character is due to be added some time after E3, according to the game's community manager.