Briers' agent, Christopher Farrar, said Monday that the actor died at his London home on Sunday. A former heavy smoker, he had suffered from emphysema.
Briers starred in the 1970s sitcom "The Good Life" as Tom Good, a man who decides to quit the urban rat race for a life of self-sufficiency in suburbia.
The show, which contrasted the back-to-the land Goods with their conventional neighbors the Leadbetters, made stars of its core cast—Briers, Felicity Kendal, Penelope Keith and Paul Eddington—and is regularly voted one of the greatest British sitcoms of all time. Broadcast in Britain between 1975 and 1978, it aired in the U.S. as "Good Neighbors."
Briars also starred in the comedy-drama "Ever-Decreasing Circles," the Scottish Highlands drama "Monarch of the Glen" and a host of other shows.
In later life he became well-known for Shakespearean roles. He joined director Kenneth Branagh's Renaissance Theatre Company in 1987 after deciding, he said, that "I had gone as far as I could doing sitcoms."
For Branagh he took on roles including King Lear, Malvolio in "Twelfth Night" and the buffoon Bottom in "A Midsummer Night's Dream."
He also appeared in several Branagh-directed films, including "Henry V," "A Midsummer Night's Dream," "Hamlet," "Peter's Friends" and "Mary Shelley's Frankenstein.
Branagh remembered Briers as "a national treasure, a great actor and a wonderful man. He was greatly loved and he will be deeply missed."
Briers also was the voice of rabbit Fiver in the much-loved animated animal feature "Watership Down," and narrator 1970s children's cartoon "Roobarb."
On stage, he was associated with the work of British comic playwright Alan Ayckbourn, playing leading roles in "Relatively Speaking," "Absurd Person Singular" and "Absent Friends."
Born Jan. 14, 1934, Briers trained at the Royal Academy of Dramatic Art in London and worked consistently in theater, film and television for more than half a century.
His latest film credit is in the recently released "Cockneys Vs. Zombies."
He said he had no desire to retire, but complained in one of his final interviews that the chronic lung disease emphysema was slowing him down.
"The ciggies got me. I stopped 10 years ago, but too late," he told the Daily Mail newspaper last month.
"It's totally my fault. So, I get very breathless, which is a pain in the backside."
In 1989, Briers was named an Officer of the Order of the British Empire by Queen Elizabeth II for services to the arts.
Among his peers and fans, Briers was much appreciated for his humor and self-deprecating wit. He said of one run in the title role of "Hamlet": "I may not have been the best Hamlet of my generation but I was certainly the fastest."
"On the opening night I took 24 minutes off the running time, and I think it must have been the only 'Hamlet' in recent times where people were able to get out to the pub afterwards for a drink," he said.
Briers married the actress Anne Davies in 1956. They had two daughters.