Son of Peter Walter III, Peter Walter IV joined the United States Marine Corp in 1955. At age 25 he becomes the commander of spacecraft Cosmo.
In 1962, Commander Walter's ship is struck by a blue matter energy beam from a portal in Earth's atmosphere (created by Rabbit 's core on Earth), and it is destroyed. Walter himself is also struck by the beam.
In the destruction of the Cosmo spacecraft, Commander Walter was briefly assumed dead as a flight engineer named Dwight claimed to have seen the explosion hit Walter in the chest. However, Commander Walter lived to save Dwight from the wreckage and became known as Commander Cosmo.
In 1988, Commander Cosmo enters the Achilles Rift and is transported to Universe Omega, where he seals himself inside a dying star, thus accidentally creating the Necrostar. A year later, both Cosmo and the Necrostar are imprisoned by Jumbo the Time Guardian.
Commander Cosmo has many superhuman abilities granted to him by the blue matter, such as a "sunbeam stare," super strength, unassisted flight, and the ability to survive unaided in space.
In 1962, Commander Walter's ship is narrowly missed by a blue matter energy beam from a portal in Earth's atmosphere (created by Rabbit's core on Earth). The beam mingles with human DNA from a Russian space probe and creates the Daughter of Space.
In 1966, Commander Walter's patrol vessel is destroyed by the Daughter of Space, who then saves him and takes him deeper into space. Together, they wreak havoc across the universe, destroying the spacecraft Delarue and at least 8 moon bases before they are stopped by Commander Cosmo.
Following the Astronaut's death, a piece of the Necrostar takes over his corpse, creating the Necronaut.