Every time Doomsday (DC Comics) is killed, he returns from the dead immune to what previously killed him.
Whenever Mitch Shelley/The Resurrection Man (DC Comics) is killed, he returns to life with a new power that correlates in some way to his death.
Guardians (Destiny) who use Radiance comes back to life even if in a Darkness Zone which negates resurrection and gains a boost in Light and Solar power.
Dominus Ghaul (Destiny) after stealing the Light, is able to resurrect himself and become immortal.
After being killed by Tommy Jarvis and resurrected by a bolt of lightning, Jason Voorhees (Friday the 13th) has developed superhuman strength, near-invulnerability, accelerated healing, and virtual immortality.
Clifford Zmeck/Major Force (DC Comics) is able to revive an endless number of times growing more powerful with every death due to his connection to the quantum field.
Madara Uchiha (Naruto) resurrected himself into flesh.
Orichalcos Gigas (Yu-Gi-Oh!) resurrects itself every time it dies, cumulatively gaining 500 more attack points.
Every time Geras (Mortal Kombat 11) is killed, he returns to life stronger and more powerful, allowing him to fight on par with gods such as Raiden.
After being killed a second time, Yusuke Urameshi (Yu Yu Hakusho) underwent the Atavism of the Mazoku, becoming a more powerful half-demon.