A hero published by Marvel Comics. Quicksilver was created by Stan Lee and Jack Kirby and first appeared in X-Men #4 in 1964.

Pietro Maximoff is the son of Eric Magnus Lensherr, the powerful mutant known as Magneto and his gypsy wife Magda. Magda fled Magneto and hid herself, fearing for the child she carried after discovering his powers and what he was capable of. Magda found her way to Wundagore Mountain and the realm of the evolved animals that were the subjects of the High Evolutionary. Bova, the bovine nursemaid, helped Magda to give birth to twins, Pietro and his sister Wanda. As soon as she was able, Magda fled Wundagore, hoping that her children would be safe if Magneto was to find her. It is believed that she died soon after.

Bova was soon approached by Robert Frank and his wife, who had formerly been the heroes the Whizzer and Miss America. The couple were expecting a child, but the pregnency had experienced difficulty and so the two did what any couple would do, which is turn to the nearest highly evolved cow that they could find. Mrs. Frank went into labor, but died due to complications. The baby was stillborn, and in an attempt to assuage Frank's grief, Bova presented Pietro and Wanda to him as his own children. Overcome by his loss, Frank fled leaving Bova with the twins and further complicating parental issues for the pair in years to come.

Bova finally gave the twins to a gypsy couple, the Maximoffs, to raise. The pair was raised by the Maximoffs for years, believing them to be their natural parents. Upon reaching puberty, the two began to show amazing powers. Pietro found that he could run and move at incredible speeds. When his adoptive father was caught trying to steal food for the family, the local villagers attacked their family. Pietro grabbed his sister and fled, but soon found that they had become lost and could not find their way home. This additional trauma in their already fractured life, caused the pair to suppress their memories of the Maximoffs.

For many years, the two wandered until Wanda's powers caused a fire which burned down a home. Accused of being a witch, she and her brother were attacked by some villagers, but the pair was rescued by their natural father Magneto, though none of them knew of their relationship. The pair was recruited by him and they became part of the Brotherhood of Evil Mutants.

The Brotherhood fought against the original X-Men on a number of occasions. The pair took the names of Quicksilver and the Scarlet Witch and they stayed with the team until some of their members were taken into space by the mysterious Stranger. The twins returned to their Balkan home for a time, but were eventually asked to join the Avengers. Some of the founding members of this reknowned super hero team were leaving for personal reasons and Quicksilver and his sister, along with the bowman Hawkeye were asked to join. Fighting under the leadership of Captain America, the group made quite a strong showing for themselves.

During a battle with the Sentinals, Quicksilver experienced some serious injuries. He was discovered by the Inhumans and they took him in and treated his injuries. During this time, Quicksilver and the Inhuman named Crystal became romantically involved. They eventually married and Quicksilver went to live on the Moon with the rest of the Inhuman royal family. During this time, he worked with their militia.

The twins searched for their past and eventually discovered that neither the Maximoffs or the Franks were their true parents. Magneto eventually found Bova and discovered the truth of who his offspring are. Though the twins know who their father is, they have not embraced his beliefs.

Quicksilver and Crystal had a daughter named Luna, but their relationship became strained during this time, and Crystal cheated on her husband with a real estate agent. Their marriage broke up and Quicksilver began to seemingly breakdown from the strain. He sided with the agencies of the U.S. government and betrayed his fellow Avengers to them. He fought his former teammates in the company of a group of LMD versions of the Zodiac. He later attacked the Fantastic Four and even teamed with former Soviet agents in an attack on the Avengers. Eventually it was discovered the Quicksilver was being influenced by the Inhuman Maximus.

Quicksilver then joined the second incarnation of the team known as X-Factor. This team was run by the U.S. government, but evenually folded due to internal strife. Soon afterward, Crystal and Quicksilver were reconciled, but were separated by the sacrifice of Crystal and the other Avengers to defeat the villain Onslaught. Quicksilver joined the Knights of Wundagore, leading the evolved animal warriors in the defense of the mountain and the High Evolutionary. Crystal has since returned to Earth and the two continue to mend their relationship.