Abraham Whistler has not yet been seen in regular 616 Marvel continuity. He was first created and used in the 1990's Spider-Man animated series. After this succes, he was used in the Blade movies in the same role as in the cartoon, a teacher to Blade. It is a rare occurrence that a comic-character is first seen in a movie or on tv before it stars in a comic.
His first appearance in a comic can be found in the comic book movie adaption of the Blade II movie, but his face is also seen on 2 covers of the MAX imprint Blade comic from Marvel Comics.
Next to nothing is really known about Whistler, we do not learn much of his history or past just what we learn from his present appearances in the films. We learn that he had a family that were butchered by a pack of Vampires and that caused him to pick up the title of Vampire hunter. He stumbled across a young Blade who was preying on humans in the street and takes him in and teaches him how to kill Vampires. Whistler is tech savant and a good engineer as well as weapon manufacturer making all of Blade's custom weapons for killing Vampires.
In Blade he is introduced as a scruffy and tattered old man but seems to be tough as nails. He is introduced when Blade brings Dr. Karen Jenson to there Base after she has been bitten by a Vampire and Blade hopes to save her. We learn of the very little there is on his past in this movie that a Vampire tortured him and his family and made him choose who lives and who dies and then killing them all. The main villain from the movie Deacon Frost and his group of Vampires find Blade and Whistler's Base when Blade is away. For an old cripple Whistler puts up a good fight taking out at least three of Frost's Men but they eventually capture him and feed upon him. Blade returns to find Whistler and is completely torn and emotional, he gives Whistler a pistol because Whistler wishes to commit suicide rather than turn into a Vampire. Blade leaves as the sound of a gunshot echoes in the background.
In Blade II it is revealed that Whistler's suicide attempt was a failure. Blade finds him chronically frozen when they talk Whistler reveals that he failed his suicide attempt and was kidnapped by a group of Vampires who took him to the Czech Republic were the tortured him everyday. When they safely leave, Blade injects Whistler with a cure for Vampireism. Blade and Whistler are called to The Shadow Council which is all the world leaders of Vampires to ask help deal with the Reaper epidemic. Chupa a Vampire from a group known as the Bloodpack who has a grudge towards Whistler attacks him viciously to the point were his only option to make it out alive is to release Reaper pheromone and the sewers where they were fighting become flooded with Reapers who devour Chupa as Whistler escapes.
Whistler's part in the third movie is rather small and tragic. Blade has been framed for murdering three humans catching the attention of the media as well as the FBI. The FBI swarm Whistler and Blade's warehouse where Whistler activates the self destruct code taking himself as well as the agents inside the hideout.
Spider-Man the Animated Series
Abraham Whistler appears in several episodes of Spider-Man the animated series as Blade's mentor.
Abraham Whistler was actually an original character created for Spider-Man The Animated Series, but was later used for the Blade movies.
He was quite different in Spider-Man the animated series however, for one he was British, furthermore he was far more clean-cut in appearance, with short hair and no facial hair. He was also younger then the Whistler of the films.
Blade Live Action TV Series
The live action tv series starring Blade also show Whistler's background a little more. One episode shows that Whistler got his trademark limp from a young Blade, who escaped his father's house and broke Whistler's leg in an attempt to get away from him. The boy was later taken in by Whistler and tought to become a vampire hunter by him.
Powers & Skills
Whistler has no superhuman abilities besides his short time as a Vampire but he makes up for it in skill. Whistler is a master in several forms of martial arts, an expert marksman, and peak human strength. He is also a technical genius designing all the software in the many hideout Whistler and Blade have had as well as designing and building all of there special Vampire killing weapons. He also is highly skilled in the field of genetics working on way to slow down Blade's blood lust as well as creating fluid to instantly kill Vampire.