10 Best Teen Titans Episodes
5. Masks (1.9)
By far the most enduring conflict of Teen Titans' five season run is that between Robin and Slade. From the moment Robin first learned the latter's name in Final Exam, you could tell that these two were going to have quite the interesting rivalry.
Masks, which came later in season one, was the first episode to show just how deeply affected Robin is by his pursuit of Slade and makes it clear how far he will go to take him down.
The episode follows Robin as he dons the mask of a new villain named Red X as a way to get close to Slade, lying to his friends faces at every turn to protect the truth. Unfortunately, this comes back to bite him, as Slade isn't easily fooled and Robin has to make amends for betraying the trust of his team and closest friends.
Masks would not be the last episode in the series, nor on this list, to show just how unhealthy Robin's pursuit of Slade was, but it was the first to and it certainly made a statement in the process. Of all the original concepts this show brought to the table, Red X is by far one of the most memorable.