Birdie is a redeemed villain from the Street Fighter series, first appearing as a non-playable opponent in the original Street Fighter, before becoming playable in Street Fighter Alpha. He is an obese British bar bouncer who fights using chains.
He returns to the series in Street Fighter V, no longer employed by Shadaloo, and with an updated look, looking noticeably paunchier than previous incarnations. In V, he's living as a freeloading house guest in Karin Kanzuki's estate, where he spends all of his time eating, sparring with Karin, and acting as a security guard.
Birdie's character is very fitting of the "dim-witted brute" archetype. He is violent, short-tempered and generally unkind to others around him, and has an unsettling habit of licking his chain attached to his wrist before and/or after combat. However, he is shown more positively in the expanded media of Street Fighter; for example, in the Alpha manga, he is shown to be friends with Ryu, and allies himself with Chun-Li.
In Street Fighter V, Birdie is presented as more of a comical glutton who enjoys eating, even during fights. Although still just as rude and brash, Birdie seems to be noticeably less aggressive towards others, likely due to the fact that he is no longer a part of Shadaloo. He is also very conscious of his mohawk and hates wearing any hats, as he believes it would mess up his hairdo.