What is the longest living pet you have owned?

Our family had a cat who lived almost 20 years. We'd gotten him as a kitten when my brother and I were teenagers, and he stayed with my parents after we moved out. He'd developed thyroid problems when he was around 14, but my parents kept it under control with regular vet checks and medications. He finally passed away about a year and a half ago when he developed a tumor on his head. He was too old and weak to survive a removal surgery, so my parents just kept him comfortable until the tumor was too large and he was in pain. Even though he's been gone awhile now, it's still weird going to my parents' house and not seeing him.

I've had birds, but just budgies (who don't live all that long compared to other parrots), and now my cockatiel. We're unsure of my cockatiel's age- he's a rescue - but the vet thinks he's a senior bird. I hope he's still around awhile though, since 'tiels can occasionally live into their 30s (around 20 is more normal).