Best known as the cowboy cop in the '70s hit McCloud, the folksy actor also fought passionately for the environment and against world hunger

In a film and TV career spanning half a century, Dennis Weaver played doctors, judges, anchormen. But as his friend Valerie Harper, who twice played his wife in TV movies, says, "I'll always think of Dennis in his cowboy boots and hat—whether it was as Chester or McCloud, people loved him." She's referring, of course, to Chester Goode, the earnest, limping sidekick to Marshal Matt Dillon in Gunsmoke from 1955 to 1964, and Sam McCloud, the folksy New York City lawman of the '70s crime series. "You could count on him. He was steady. [He had] a wonderful American quality."

That, and a boundless optimism. "There was never anybody with higher spirits than Dennis," says his wife, Gerry, who was with him when he died at 81 of complications from prostate cancer Feb. 24. Certainly there were few actors with more daring. "Dennis was the first actor who ever came up to me and asked to perform his own stunts," says Steven Spielberg, who made his movie debut directing Weaver in the 1971 man vs. truck thriller Duel.

The Missouri-born Weaver, who got his professional start on Broadway in the 1950s before heading out to Hollywood, made friends wherever he went. "Dennis and I became practically like brothers," says his Gunsmoke costar James Arness, 82. "And it's been a friendship that has remained for 50 years." Former Dallas star Linda Gray, who credits Weaver with launching her career in 1973 by giving her a bit part on McCloud, says, "As an actor, Dennis always had a twinkle."

And as an environmentalist, he had a vision. In 1989 he and Gerry built a solar-powered split-level home in Ridgway, Colo., out of old tires and recycled aluminum cans. "People said we were going to live in a garbage house," he said years later. "Now, when they see the finished product, their minds totally change." Weaver also crusaded against world hunger. As president of LIFE (Love Is Feeding Everyone), a charity he helped to run in the 1980s and '90s, he fed up to 150,000 needy people a week in L.A.

Weaver kept up his acting and his activism even after being diagnosed with prostate cancer in 1991. "He was in a series [ABC Family's Wildfire] when it caught up with him again," says Gerry, 80, with whom he had three sons: Rick, 57, a producer, Robby, 52, a director, and Rusty, 47, a songwriter and producer. "I was alone with Dennis when he died, and he just fell over into my lap, very quickly. He left in a very peaceful way."