Niklaus Mikaelson, or Klaus, is a character from The Vampire Diaries novels and the CW shows The Vampire Diaries and The Originals. Klaus is an Original vampire and the first Original Hybrid, meaning he's half-vampire and half-werewolf. His hybrid status stems from his mother Esther's affair with Ansel, a werewolf pack leader, which gave Klaus a secret werewolf heritage. Klaus triggered his werewolf gene after making his first human kill as a vampire