Whistler, played by Max Perlich, is a character in the television series Buffy the Vampire Slayer.
Whistler is an enigmatic demon who appears in Season Two. He first appears in a flashback in the episode "Becoming, Part One" in which he approaches a dirty and destitute Angel on the streets of New York City. He describes his duty as maintaining the balance between good and evil, and claims that Angel is destined to be a force of good. He then takes Angel across the country to Los Angeles where he points out the young Slayer Buffy Summers as she is called to her destiny, and later at her home, where she is clearly distraught over her Slayer duties and hearing a massive argument between her parents. Seeing her allows Angel to decide to turn his life around, and to help Buffy in her duty as the Slayer. Whistler does not interfere again until he learns that Angel, now without a soul, plans to awaken the demon Acathla. He confronts Buffy and tells her that Angel was never supposed to lose his soul. In fact, it had been his destiny to stop Acathla, not bring him forth. He informs Buffy that she will have to kill Angel to stop Acathla if he is awakened, which ultimately comes to fruition.
Whistler subsequently appeared in the Buffy the Vampire Slayer Season Eight comic book "Riley: Commitment Through Distance, Virtue Through Sin" (2010) wherein he is established as Angel's confidante and guide in taking up the Twilight mantle and leading an anti-Slayer coalition. The Season Eight sequel Angel & Faith (2011–2013) features Whistler as one of its primary recurring antagonists; he wishes to restore magic to the world following Angel's betrayal of their cause in Season Eight, and is shown to be exceptionally strong. The issue "The Hero of His Own Story" (2012) depicted Whistler's origin story: the child of a demon and a servant of the Powers That Be, he was blessed with foresight by the Powers and made their agent to create an equal balance of good and evil in the world. He had expected Buffy and Angel to create a paradise in the Twilight dimension where all the good people could live happily ever after, while still maintaining balance because a few million people would die before Buffy and Angel were ready to bring the worthy ones over. Evil demons and humans would be abandoned on Earth and die when it was destroyed upon completion of the Twilight dimension and therefore free Whistler of his obligation to maintain the balance of Earth. In the present day, in a world without magic, he is separated from his power of prophecy and has become unhinged. Before the loss of magic he received a vision of a dystopian future if magic does not return to the world. In England, he works with the half-demon siblings Pearl and Nash to gather all the magical items he can to unleash a magical plague that would, at the cost of a few billion lives, transform the surviving humans into a magical species. In the final arc, "What You Want, Not What You Need" (2013), Whistler takes the energy from all the magical items and turns it into an orb of pure magic which he plans on having Pearl and Nash fly into the upper atmosphere to mutate the world. In the final battle with Angel and his team, the plague orb mutates or kills several people in the London Borough of Hackney. During their confrontation, Angel forces Whistler to absorb some of the orb's magic, which clears his addled mind. In an act of redemption, Whistler sacrifices his life to destroy the orb entirely. Before he dies, he thanks Angel for saving him from himself and says doing the right thing is more important than balance. Angel mourns the death of his mentor, and subsequently decides to stay behind in the newly christened "Magic Town" suburb of London where he anticipates there will be trouble among its mutant populace.
Whistler has also appeared in the non-canonical Buffy post-Season Seven novel Queen of the Slayers, coming to Buffy in a dream to help her get back her confidence in order to defeat a rogue army of Slayers, three Hellgods, and a vampire sorcerer.