Sorry that this one is so obvious, but there is literally no other answer. We played around with the idea of Fez as the best character on Euphoria a little bit, but how can anyone possibly go any other direction, especially after the way that finale ended? Zendaya is Euphoria's headlining star, and at no point during the show's first season was that ever not absolutely abundantly clear.
Whether she's holding it down in rehab, going fully-manic for a Pepe Silvia-esque investigation, or literally spiraling out of control in the show's musical finale, her A-game has proven to be a force to be reckoned with. Not to mention her narration, which anchors the whole show, and literally sets the tone for the entire show.
This isn't just the best character on the Euphoria—it's one of the best characters on TV, already. The Emmys might not be in the cards for a full year, but we can get the Golden Globe countdown ready.