Several Marvel Comics characters have been known as the Whizzer.

Bob Frank

The first Whizzer is a fictional character and a superhero created for Atlas Comics in the 1940s.

Dr. Emil Frank and his teenage son Robert were on a trip to Africa. Bob was bitten by a deadly cobra. As the cobra turned on his father, a mongoose lunged at it from the bushes, landing atop it and killing it. Knowing that his son will not survive if a blood transfusion is not performed soon, Dr. Frank has the brilliant idea of taking the blood of the mongoose and giving it to Bob. As Bob awakened, the strain proved to be too much for his father, who suffered a heart attack and died. The mongoose blood, reacting to his already mutant physiology, had given Bob amazing speed. Donning a gaudy yellow outfit, complete with fin atop his head and green cape trailing behind (later to be changed to a yellow and blue bodysuit), Bob calls himself the Whizzer.

The Whizzer lasted few issues on his own, appearing again in the All-Winners Squad at the end of 1945, and later in the modern day as a short-lived member of the Avengers. He erroneously believed himself to be the father of the mutant twins Quicksilver and the Scarlet Witch. He died in Vision and Scarlet Witch #3; the twins learned the identity of their actual father (Magneto) in #4.

The Whizzer has also been retconned into the recent Invaders stories, and remains a favorite among Golden Age fans, even if only for his insane origin.

Stanley Stewart

While running alone on a country road, Stanley Stewart passed through a dense, luminescent fogbank. When Stewart emerged from the fogbank, he discovered that he could alter his perception of time so that the world appeared to be in slow motion. Every day after that Stewart found that he could run faster and farther than the previous day. Six weeks after running through the fogbank, Stewart broke the sound barrier while on a 200 mile sprint. It was at that point that Stewart decided to become a costumed crimefighter.

Stewart originally wanted to call himself the Boomer, but instead decided to call himself the Whizzer at his wife Madeline's suggestion. He works with the Squadron Supreme, in an alternate universe in Marvel.

The Blur

In J. Michael Straczynski's reimagining of the Squadron Supreme, Supreme Power, the Whizzer's counterpart is a young african american named Stanley Stewart, who kept his powers a secret until show business agents offered him a product endorsement contract. Until then, Stanley had only been spotted as a blur (hence the name) and is existence was considered an urban myth. At Nighthawk's urging, the Blur has begun working as a vigilante.