And if we're just talking about the longevity of biological lifeforms in general, then I may as well mention Sarlaccs.
They have estimated lifespans of 20,000-50,000 years:
https://i.imgur.com/yifasPc.jpg
-TNEG: Alien Species
Well, this looks like a good place for a list. You're making be catch the star wars minute details obsessions bug again, Sheev.
Wookies live 400+ years
Anzat, Yoda's species, Hutts, a few other randoms live 1,000 years
My begrudging answer for the top place is Gen'Dai, known to live 7,000 years
My accepted, though incorrect answer is Nati, who live for possibly 10,000+ years if circumstances are right.
If we're counting creatures,
Space Slugs (exogorths) live in excess of thousands of years
so do Space Wasps
The star dragons live to about 2,000
Sarlaacs take the cake at 20,000 to 50,000 years
There are so many more I know that I was thinking of last night, but I was too tired and didn' want to write in that condition, but now I can't remember them anymore. These are the longest living ones, though.
Maybe the Killiks, I don't know, they live like millions of years, right?
And the Celestials probably had incredible lifespans. Who knows.