"Listen, I am one of the world's foremost authorities on the Quantum Realm. And the only thing about it that I can say for certain is that we don't know much of anything for certain."
William Foster is a former SHIELD scientist and researcher, as well as a former member of the directing council of SHIELD. The grandson of sharecroppers in the south, Bill was raised in a poor family just outside of Chicago, Illinois. Despite coming from a poor background, he worked hard to put himself through school and found his calling in the field of engineering. As a young man, Bill would meet and form a friendship with another brilliant scientist by the name of Hank Pym. Together the two would begin putting together theories concerning subatomic particles and possible multiple dimensions. While their work was completely disregarded at first as, fantasy, it drew the eye of one Howard Stark, who was curious about the potential that the two showed. He invited them to come work for him while keeping a close eye on their work.

Through trial and error, eventually Hank managed to find a formula that synthesized a subatomic particle which would shrink the distance between atoms, for lack of a better term. The pair quickly discovered that exposure to these particles would alter brain chemistry over time (quicker for some than others). Fortunately, Bill was able to develop a helmet that prevented these deletrious effects from taking place. Despite completing the suit, the pair realized that the technology could be used to great harm if it fell into the wrong hands. Not necessarily trusting Howard Stark's intentions, Hank demanded that if SHIELD was going to use the Pym Particle, it would be with him as the operator of the suit. SHIELD agreed, and Hank became a full-time operative for the group, while Bill remained a scientific advisor and also moved into analytics. He moved up the ranks and was well-respected by everyone at SHIELD. Eventually he was even named a member of SHIELD's ruling council, serving alongside Stark and SHIELD co-founder Peggy Carter. However it was here that Foster and Pym's friendship/partnership hit a rough spot, as Hank's wife Janet seemingly died on a mission at the same time Howard and Foster were attempting to figure out the exact formula behind the Pym Particle. Angered, especially at Bill, Hank resigned from SHIELD entirely. Shortly thereafter, disgusted with what had happened and trying to find a way Janet might have survived into the Quantum Realm, Bill also resigned from SHIELD and entered the private sector. It was also at this time that Bill married a woman named Jeannine and had a daughter named Ava.

While in the private sector Bill teamed with industrialist and scientist Anson Starr to attempt to create a way to traverse the Quantum Realm, resulting in a Tunneling Device and the Quantum Traversal Vehicle or QTV. However a test of this equipment went terribly wrong, resulting in the death of Bill's wife and his young daughter's bombardment with Quantum Particles, which caused her Quantum Signature to enter into a state of flux. It took several years for her condition to deteriorate to the point of needed assistance, leading to Bill and Starr to create a suit that regulated her condition and allowed her to utilize her natural phasing ability to some degree of control. However, after the death of Anson Starr, his son Elihas took control of the company and coopted Ava and Bill into becoming industrial saboteurs in exchange for continued maintenance and use of the suit that was now keeping Ava alive. Bill kept this part of his life a secret, even after returning to SHIELD in an advisory capacity.

Several years later, Bill was asked by new SHIELD director Thaddeus Ross to unlock some of the original research files concerning the Ant-Man project. Foster declined to do so, though Ross indicated that the next time he asked it wouldn't be a request. This led Bill to contact SHIELD agent Hope van Dyne, the daughter of his old friend. After reconciling with Hank, Bill abandoned his work with SHIELD for the time being and went underground, with the trio concocting a plan to stop SHIELD from duplicating the Ant-Man technology. Bill posed as a buyer who hired thief Scott Lang to break into Hank's home and "steal" the original Ant-Man suit. After Scott did so (and was promptly arrested when Bill didn't arrive for the "sale"), Foster and Pym directed Scott to become Ant-Man and escape from jail, going underground with them to train in the use of the suit and forming a plan to break into a SHIELD research facility and destroy the data that SHIELD had amassed. Unfortunately however SHIELD did manage to create a replica suit before the plan could be ennacted, though without the medical safeguards that Foster had invented. This caused its wearer, Eric O'Grady, to have an immediate negative reaction to the Pym Particles, losing touch with reality once he began using the suit regularly. As Scott Lang fought with O'Grady, Foster helped Hank and Hope finish destroying the research facility and escaping via a smuggled in shrunken tank.

Following the defeat of O'Grady, Foster continued to work for Pym Technologies, before being forced to go on the run with Hank and Hope as a result of Scott's actions in Budapest during the Avengers Civil War. They continued to work on Quantum Technologies while on the run, hoping to be able to rescue Janet from the Quantum Realm (as well as Bill hoping to find a cure for Ava's worsening condition.) They were surprised after building the Quantum Tunnel, however, to have a second fully functional QTV come through unannounced, carrying four time travelers from an alternate future as well as Janet van Dyne. Bill and the Pyms turned themselves into SHIELD in order to get Tony Stark's attention and warn him about the impending arrival of the Chitauri. Following this, Bill was released without charges and, with Janet's help, was able to stabilize Ava's condition while also seeing Elihas Starr arrested for his illegal activities.

Alternate Timeline

In the alternate timeline of Infinity War, the four time travelers did not travel back, causing Bill and Hank to recruit Scott Lang to once again help them in their endeavors. However the two threads of his life came crashing into each other, as he was ordered by Starr to secure Hank Pym and his technology for his own use. Bill reluctantly did so only to ensure his daughter's continued access to the suit keeping her alive, but eventually turned on Starr and helped free the Pym's from captivity, before watching them enter the Quantum Realm to find Janet van Dyne. Bill was unable to stop Starr from causing damage to a nearby dam in his attempts to gain control of the Pym technology, and almost lost his daughter completely when the suit was deactivated for a prolonged period of time. Thankfully she was stabilized, but not cured, by Janet van Dyne, who had herself been mutated by Quantum Particles into gaining certain healing powers.

Bill was eventually killed by "the Snap" of Thanos which wiped out half of all life on Earth.

Powers & Abilities

  • Genius Scientist: Bill Foster is a versatile scientific mind, as he helped refine many of the theories and pieces of equipment that Hank Pym would use to develop the Ant-Man technology. Most specifically, Foster is credited with inventing the regulator helmet that prevents the deletrious mental effects Pym Particles can have on the human mind. He is also considered one of the world's foremost experts on the Quantum Realm, though that is admittedly based on very little information.
  • SHIELD training: Though he was never a combat agent, it is possible that Foster has received rudimentary combat training from SHIELD, given that he at one point served as a member of SHIELD's ruling council in the late 1980s.


Bill Foster possesses no special abilities that would protect him from normal wear and tear of a human body. He has never been documented as using the Ant-Man technology (though it is speculated he may have been the mind behind the inverse Giant Man technology, which comes with its own set of weaknesses.)

Film Details

Bill Foster appears in the following films in the Earth-11584 continuity. In all cases he is portrayed by actor Laurence Fishburne.

  • Ant-Man (2015)
  • Ant-Man and the Wasp (2018)
  • Avengers: Infinity (2019) [mentioned only]
  • Avengers: Infinity Gauntlet (2019)
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