The series finale of Battlestar Galactica was an awful ending to a wonderful show. But the entire last season was lackluster imho. Kinda the same as the Lost series finale and final season. But some of Lost's earlier season finales were amaaaazing.

The season 5 finale of Buffy the Vampire Slayer has always been one of my favorites.

Buffy Summers
1981-2001

Beloved Sister
Devoted Friend

She saved the world
A lot


Dexter's last season finale was kinda amazing too. Alias Season 2 finale was epic. I nearly died from the craziness of it. It's one of those season finale that makes you ache for the summer to rush by so that the fall premieres can start up again.