Which reptile lives the longest?

Gaining the title Longest-Lived Reptile, the Giant Tortoise in captivity has been known to live longer than 200 years, and there's every reason to believe that testudines in the wild regularly hit the 300-year mark. These reptiles move extremely slowly, their basal metabolisms are set at an extremely low level, and their life stages tend to be comparably stretched out.

Source: ThoughtCo.