After leaving high school behind in the season 3 finale, Buffy the Vampire Slayer struggled to find its footing in young adulthood. Season 4 was an epic mix of highs and lows, with each episode being a toss-up between a series-defining masterpiece and a well-intended misfire. In the wake of that often disappointing 22-episode run, it was clear that Buffy needed a change of pace. By perfectly blending the shows signature supernatural elements with relatable, grounded drama, season 5 is brave, moving, and masterful thanks, in no small part, to the introduction of Buffys (Sarah Michelle Gellar) brand-new little sister Dawn, played by Michelle Trachtenberg, who tragically passed away on Feb. 26, 2025.In what remains one of the best teen drama twists of all time, season 5s opening episode drops a bombshell before a quick cut-to-black: the young girl briefly shown in Buffys room is, according to their mother, her little sisterdespite never being part of the series prior to this moment. As the season continues on, Buffy eventually learns that Dawn was created by a group of monks, transformed from a magical key into a person that Buffy herself would ultimately die to protect from an angry god. While this premise is as harebrained as it gets (and par for the course in the series supernatural wheelhouse), Dawns evolution from annoying little sister to beloved pillar of the show all circles back to the brilliant writing elevated by Trachtenbergs vulnerable and moving performance.Dawn herself could have easily devolved into nothing more than a plot device. Her presence in the fifth seasons story is straightforward and often predictable, and, in less capable hands, its easy to see how one-note this key-turned-sister couldve been. But from her very first full episode on the show (titled Real Me, season 5 episode 2), Trachtenberg imbues her with a tangibility that is only matched by Gellars early work on the series as Buffy herself.Theres a gentle touch behind every move Dawn makes, where her charming, troublemaking streak blends with her heartbreaking, grounded fear layered with a heavy dose of supernatural symbolism. Dawn questions whether or not shes a real person deserving of love, mirroring the fears of many teenagers as they try to develop into themselves. Dawn acts out when Buffys larger-than-life stakes overshadow her teenage drama, injecting an even stronger inferiority complex against Buffys godly position within her family and friend group.In one of Trachtenbergs greatest moments on Buffy, Dawn and Buffy regroup after a fight with the seasons Big Bad, and Buffy asks if Dawn is alright. Dawn asks why Buffy cares, shes not really her sister, after all. Shes just an object that a group of monks made flesh, why should Buffy concern herself with her feelings? Whos to say she even has them? But when Buffy takes her own blood and clasps Dawns bloody hand within her own, its clear that these two women are bound for life. Even without the Summers blood running through her veins, Buffy loves Dawn, and no amount of cosmic intervention could change that.While Gellar is often the focal point of the scene, Trachtenberg gives such a stunning performance, even after her lines have finished. You can see as she puts up her walls, preemptively shutting Buffy out before her sister can hurt her by insisting that shes not a person at all. Those walls slowly come down throughout Buffys heartfelt speech, genuine love and surprise clouding Trachtenbergs wide, blue eyes. When Buffy finally hugs her, her face fully collapses, crying into her sisters shoulder as she finally admits that shes just a scared kid, facing problems and obstacles far beyond her reach.Its that admission that defines Dawns arc throughout the rest of the season, elevated by the absolutely pitch-perfect performance given in that moment. Nine episodes later, when Buffy tells Dawn that the hardest thing in this world is to live in it before she jumps to her own death to save her sisters life, its that blood-tying moment that Buffy flashes back to. Of course, its to explain just how and why Buffy can sacrifice herself in Dawns place, but its also to remind audiences that Dawn is, truly, just a scared kid who doesnt believe her life is worth saving, especially over Buffys.Even if Dawn didnt believe she was worth Buffys sacrifice at the time, Michelle Trachtenberg made us believe she was. She made us believe she was the little sister we never had, but always wanted; she made us believe in the power of teenage whims and the weight of heartache and sorrow on a soul too young to have gone through so much; she made us believe in the magnitude of both being a teenager and being a lynchpin in one of the greatest supernatural stories ever told.As the series goes on, Dawn becomes further enmeshed in the canon, despite only appearing in the final three seasons. She becomes Spikes (James Marsters) odd-couple friend, she becomes Tara (Amber Benson) and Willows (Alyson Hannigan) number one shipper before it was cool, and she becomes the narratives beating heart, long after Buffy herself lost some of the light that used to shine in her eyes.Trachtenberg brought humor, heart, light, and relatability to Dawn that allowed her to become one of the series most iconic figures, picking up the baton from Gellar to bring grounded, teenage drama back into a series that knew its hero needed to grow up. While fans have rallied for decades behind their assertions that Dawn was annoying and stilted the shows evolution, this one-dimensional take on this ultimately iconic character diminishes not only importance of the teenage aspects of Buffy to the shows everlasting legacy, but also the incredible performance Trachtenberg delivered across 66 episodes.In the twelfth episode of the final season, Xander (Nicholas Brennan) sits Dawn down for a pep talk. With their house overflowing with potential slayers and an apocalypse looming on the horizon, Dawn is feeling useless and frustrated as her sister and their friends all prepare for battle. He tells her that he knows what its like to not be chosen, to not be special. Youre not special, he flat-out tells her. Dawn takes a tearful pause, Trachtenberg plays her humility and disappointment with a marked grace; but Xander isnt done: Youre extraordinary. Shes special not because she has infinite power and a calling to save the world, but simply because she cares enough to stand by those who do. If Buffy herself represents heroism by force, Dawn represents heroism by choice, inspired by her sister to do what is right and good, no matter the cost.Join our mailing listGet the best of Den of Geek delivered right to your inbox!Extraordinary feels like the perfect word to describe both Dawn and Trachtenberg. The kind of perfect storm created by a character and performance so moving and incredible that it defines the series itself, that it becomes seminal to the genre in a way that is absolutely undeniable. The world is infinitely less bright without Trachtenberg in it, but, at the very least, her performance as Dawn SummersTVs greatest little sister, still, to this daywill live on as one of the best to grace both the series and the genre itself.