Gunn is a regular human and has no supernatural abilities. He does possess great strength and martial arts expertise due to his years as vampire hunter, often being described as "the muscle" of Angel Investigations. Due to Wolfram & Hart's legal upgrade in Season Five, Gunn also has knowledge of all legal codes, both human and demon, as well as fluency in some demonic languages, knowledge of golf techniques and knows all Gilbert & Sullivan light operas.

Gunn is a fan of pop culture and often displays a detailed knowledge regarding comic books:

In the episode "Supersymmetry", Gunn threatens a man in a comic book store by referencing the specific issue of Daredevil in which Bullseye kills Elektra, even quoting from the cover blurb which reads "...One wins, one dies."

When commenting on how fast Illyria appears to move when using her time-warping abilities, Gunn compares her to three different incarnations of the Flash: Jay Garrick, Wally West, and Barry Allen. The reference elicits little response from his confused friends.