He was turned by Mary, Queen of Blood while studying at the Temple of the Ineffable Tao. His master Shoju is also turned, but the other monks retain their peaceful demeanor through zen. Kessler is asked to kill the other monks, as the Blood Red Moon believes they may pose a threat. He manipulates Andrew Bennett, Deborah Dancer and Dmitri Mishkin into fighting the monks for him. Bennett realizes the deception during their battle, and turns around to stake Kessler through the heart.
- Vampirism: In addition to the various mental and physical benefits that vampires are heir to, they also possess the ability to turn others into vampires as well. Each new vampire is traditionally subservient to the one who "turned" them, but some strong-willed vampires have been known to rebel against their masters.
- Enhanced Senses: A vampire's senses are enhanced far beyond those of a normal human being.
- Immortality: So long as vampires continue to consume blood, they will not age beyond the physical state they were in when they first became a vampire.
- Invulnerability: Vampires are invulnerable to most forms of injury (certain exceptions apply). Bullets, blades and blunt objects do little to no damage to a vampire's body.
- Regeneration: In addition to being virtually indestructible, whatever damage a vampire does in fact suffer can be healed through the consumption of human blood.
- Superhuman Strength: A vampire's strength level is several times that of a normal human being and they are considered superhuman.
- Superhuman Stamina: So long as they continue to consume human blood, a vampire can function tirelessly without rest or relaxation. However, a vampire's stamina wanes the closer it is to sunrise.
- Psychokinesis: Most vampires possess some form of psychokinesis. Some are clairvoyant, others can communicate telepathically, some possess mind control. Particularly powerful vampires can control the minds of several people at once.
- Transformation: Vampires often possess the ability to transform into a variety of creatures or effects such as bats, wolves, rats or even mist. While their physical attributes may fluctuate during such states, a vampire's mental acuity is the same as that when they are in their human shape. A vampire who transforms into an animal may also benefit from that particular animal's attributes including razor-sharp claws, fangs or the ability to fly.
- Metamorphosis: Vampires often demonstrate the ability to alter their appearance at will.
- Although this character was originally introduced during DC's Earth-One era of publication, their existence following the events of the 1985–86 limited series Crisis on Infinite Earths remains intact. However, some elements of the character's Pre-Crisis history may have been altered or removed for Post-Crisis New Earth continuity, and should be considered apocryphal.
- 1 Appearances of William Kessler (New Earth)
- 4 Images featuring William Kessler (New Earth)
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- Character Gallery: William Kessler (New Earth)