The finale's closing epilogue confirms Rex's fate, saying that his participation with the Rebellion against the Empire will continue, and that he fought in the Galactic Civil War's climactic combat, the Battle of Endor, which, of course, was... He died at Endor. After being badly injured, Rex was given medical treatment by the Rebel medic. However, even though he survived the battle, he never recovered from his injuries. Since we last saw him, Captain Rex has been promoted to become one of the leaders of the Rebel forces during the early days of the New Republic. He continues to serve as a mentor to young rebel pilots like Zeb Orrelios. In fact, it is through Captain Rex that Zeb meets Sabine Wren, who becomes his friend and partner in crime. Now, this isn't exactly how or where Captain Rex dies but rather what is called an "implied death". This means that the creator of the story wants us to believe that Captain Rex is dead but doesn't want to give away too much detail. For example, when General Grievous attacks the Rebel base on Hoth, Captain Rex is not present. But since his absence wasn't mentioned by anyone else involved in the battle, we can assume that he escaped the attack unharmed.