<Li> Jonathan Hyde as Walter Strickler, Jim's history teacher who is actually a Changeling . When Jim discovers the truth, he loses all respect for him and the two become bitter enemies . However, he remains affable toward Jim and has redeeming qualities . </Li> <Li> Kelsey Grammer as Blinky, Jim's six - eyed troll mentor . A wise and scholarly troll with a heart of gold, he serves as the brains of the Trollhunters and eventually becomes a sort of father figure to Jim . </Li> <Li> Fred Tatasciore as AAARRRGGHH!!!, a burly troll and close companion of Blinky who forms a deep bond with Toby . He was kidnapped by the Gumm - Gumms as a child, which stunted his vocabulary . Tormented by the atrocities they committed, he deserted Gunmar to live a life of peace . However, he will still fight to protect those he cares about . </Li> <Li> Lexi Medrano as Claire Nuñez, Jim's girlfriend . She is a feisty, kind, jolly, sarcastic, curious, and intelligent tomboy who enjoys books and is a talented martial artist and gymnast . She obtains the Shadowstaff, a staff capable of creating portals activated by the user's emotions . </Li>

When does blinky turn back into a troll