He was played by Brian Patrick Wade.
When Derek Hale was in high school, Ennis' pack was in Beacon Hills where one of his young Betas was killed by Hunters after "accidently" killing two of their own. Ennis reached out to Deucalion, Kali, and Talia Hale for advice and help in his quest for vengeance. Kali and Deucalion refused but Talia claimed he had the right. He scratched a spiral to signal a vendetta against the Argents that radiated across all werewolf packs.
When he attempted to retrieve his Beta's body from the hospital, he was refused and nearly attacked an employee until he was calmed by Deputy Stilinski.
Eventually, Derek asked him to bite his girlfriend Paige so she could become a werewolf. Ennis saw it as an opportunity to gain a new Beta and be in good terms with Derek's mother so he obliged. However, the bite rejected Paige and she died.
Some time later, Ennis joined the Alpha Pack after killing both his druid emissary and Betas. When they returned to Beacon Hills, he fought against Scott McCall, Derek, and his pack until it lead to his demise at the hands of his friend Deucalion.
Ennis disguised himself as a hospital orderly, tried to kidnap Isaac Lahey and fought off Scott when he tried to stop him. He was stopped by Derek. He later joined the rest of the Alphas to take out the Mystery Girl. (Read More...)
Ennis survives his fall during the battle between the Alpha Pack and Derek's pack. He is badly wounded and taken to Dr. Deaton's for treatment. His prognosis is good but Deucalion crushes his skull and kills him while he is partially unconscious. (Read More...)