There are a lot of undead characters in the comics, be it zombies like Soloman Grundy, or vampires like Morbius. There are quite a few such characters, who either are immortal or undead. Some of whom are mentioned below:
Greta Hayes was killed by her own brother and because of the way she was killed, her soul lingers between the world of the living and the world of the dead. She has many powers such as flight, teleportation and can escort souls from the living world to the other side. Also, she can change her form and pass through objects.
As his name suggests, the guy is immortal. Mitch Shelley was a lawyer, who went under a nanotechnology experiment, which obviously had some fault and he got his powers. Whenever he is killed he returns in a short while with a totally new power, which he refers to as a gift.
The wicked of the Earth have to answer to this supernatural entity. The Spectre shows no remorse and repossesses the dead bonding their himself to their souls in order to bing their killers to justice. He’s known to be extremely powerful as he’s impervious to almost every harm that can be caused. He torments and tortures the culprits eventually killing them.
The spirit of Vengence is certainly a great terror. Johny Blaze, is a guy who sold his soul to the devil in exchange for his father’s life, becoming his bounty hunter. He freed himself from the Devil’s clutches and took the matter into his own hands. And boy… does he have a sweet ride.
After being murdered by a fellow CIA Agent, Al Simmons’ body is sent to hell where he makes a deal with the devil in order to see his wife, gives his soul to a demon and leads his army. He gets to the future, 5 years into the future where he sees his wife already remarried. He then serves his purpose of freeing the Earth from the hell spawn.