During World War II, he served as a pilot in the United States Navy, flying Grumman F4F Wildcat fighter aircraft.

Under the name Billy D. Weaver, he tried out for the 1948 U.S. Olympic team in the decathlon,[3] finishing sixth behind 17-year-old high school track star Bob Mathias.

In the beginning of his acting career, he supported his family by doing odd jobs, including selling vacuum cleaners, tricycles, and women's hosiery.

While delivering flowers, he heard he had landed the role of Chester Goode, the limping, loyal assistant of Marshal Matt Dillon (James Arness) on the new television series Gunsmoke.

According to the Archive of American Television interview with Weaver, the producer had him in mind for Chester, but could not locate him, and was delighted when he showed up to audition.

To keep from losing the part, college decathlon champion Weaver settled on using a stiff leg, something "simple and consistent," allowing him still to perform all the actions needed in a Western.

Having become famous as Chester, he was next cast in an offbeat supporting role in the 1958 Orson Welles film Touch of Evil,[7] in which he played a face-twisting, body-contorting eccentric employee of a remote motel who nervously repeated, "I'm the night man."

In 1960, he appeared in an episode of Alfred Hitchcock Presents titled "Insomnia", in which his character suffers from sleeplessness owing to the tragic death of his wife.

[8] In 1964, Weaver left Gunsmoke to star as a friendly veterinary physician raising an adopted Chinese boy as a single father in NBC's one season comedy drama Kentucky Jones.

The show, about a modern Western lawman who ends up in New York City, was loosely based on the Clint Eastwood film Coogan's Bluff.

In February 2002, he appeared on the animated series The Simpsons (episode DABF07, "The Lastest Gun in the West") as the voice of aging Hollywood cowboy legend Buck McCoy.

Each three minute report featured "late-breaking news of human contact with extraterrestrials, inside stories of UFO sightings and scientific verification of alien visits to planet Earth" according to an article in the Los Angeles Times.

In the late 1980s, he commissioned architect Michael Reynolds to design and build his new residence, which incorporated into its construction various recycled materials, such as old automobile tires and discarded cans, and featured passive solar power and other ecotechnologies.

Weaver called his home Earthship, the same name given to the design concept pioneered by Reynolds and advanced by him as part of what was then a growing interest in "sustainable architecture" by environmentalists.

[19] Weaver was an environmentalist, who promoted the use of alternative fuels, such as hydrogen and wind power, through the Institute of Ecolonomics, a nonprofit environmental organization he established in 1993 in Berthoud, Colorado.

[20] Weaver was consistently involved with the annual Genesis Awards, which honor those in the news and entertainment media who bring attention to the plight and suffering of animals.

[23] There will come a time ... when civilized people will look back in horror on our generation and the ones that preceded it – the idea that we should eat other living things running around on four legs, that we should raise them just for the purpose of killing them!