Isabella (Sarah Ramos) is a teenage werewolf who is Justin's love interest and date in season two's Beware Wolf. She is part of a series of Justin's love interests that are monsters.
Justin first comes into contact with Isabella when his friends from WizTech set him up on a blind date with her. At this point he knows very little about her except what is on her WizFace, a wizard social network site, online profile. Justin and Alex talk about how everyone lies on their profile but when Isabella turns up at the apartment she looks fairly normal. However, before long she starts acting strange such as growling and playing tug-of-war over Alex's sweater. She kisses Justin and turns him into a werewolf. It can be concluded that she is a "mutt" werewolf as according to Mason only mutts change a non-werewolf into werewolves with a kiss.