Mason Greybeck is a purebred werewolf and the most major love interest of the series' main character, Alex Russo as of season three.
Mason Greybeck is the son of Linda and Grant Greybeck and has always been pressured by his parents to date only werewolves. ("Alex Meets The Parents") Mason is a purebred werewolf, unlike one of Justin's ex-girlfriends Isabella, who is apparently a mutt. ("Wizards vs. Werewolves") Mason is shown to be a great artist, just like his love interest, Alex. ("Alex Charms a Boy")
When Mason was living in London, he dated Justin Russo's girlfriend, Juliet van Heusen. Mason and Juliet were apparently in love, but somehow lost contact and haven't spoken in over three hundred years. ("Wizards vs. Werewolves")