The Unicorn - Batman: Arkham Unhinged

The alter-ego of Skitch Benson, The Unicorn was a member of The Wonderland Gang based on the character with the same name from Lewis Carrol’s Through the Looking Glass and What Alice Found There. 

A prisoner in Arkham City, he attempted to fight Batman in The Mad Hatter’s old Hat Shop, only to be taken down by the masked vigilante. He did manage to land a hit first, goring the Dark Knight in the shoulder with the horn on his helmet before his inevitable defeat.