Don't know if this is still true as to the oldest but here goes a try.

ADWAITA THE TORTOISE (1750-2006)Even with the long life expectancy of giant tortoises, an Aldabra Giant Tortoise named Adwaita blows all others away with a life lasting around 255 years. Estimates put his birth date around 1750, making him an entire generation older than the United States of America. The tortoise was originally owned by a man named General Robert Clive, an important member of the East India Company, who got addicted to opium and killed himself in 1774. Barely a toddler at that time, Adwaita bummed around for a bit before eventually being transferred to an Indian zoo in 1875, where he spent the rest of his life eating and...that's pretty much it. After his death in 2006, carbon dating on his shell confirmed his age, making him quite possibly the oldest living creature ever, and almost certainly the oldest living vertebrate.