Mr. Griffiths was known for the incisive intelligence he brought to his roles, his flawless vocal delivery and his considerable girth. Trained in the classical tradition of the British stage, he played Falstaff in several Shakespearean stage productions and later took on dozens of roles in theater, television and film.
His breakout performance came in the 1987 film “Withnail and I,” a dark British comedy about two unemployed actors. Mr. Griffiths played a character named Uncle Monty, a lecherous homosexual aesthete.
The film was a box-office failure but has become a cult classic, especially in Britain, where aficionados sometimes dress in costume and recite lines from the movie’s cryptic script.
Mr. Griffiths had a way of delivering a seemingly innocent statement with a humorous and lascivious twist. Upon meeting a young man he vainly hoped to seduce, his character said, “Do you like vegetables? I’ve always been fond of root crops, but I only started to grow last summer.”
In another scene, Uncle Monty said he could not bear to touch raw meat: “As a youth, I used to weep in butchers’ shops.”
Mr. Griffiths starred for several years in the 1990s in the British TV series “Pie in the Sky,” in which he played a pastry-baking detective.
He appeared in six of the popular “Harry Potter” films as Uncle Vernon Dursley, the guardian of the young Harry Potter. His character was a grumpy “muggle” — an ordinary human without magical powers — who treated the budding wizard, played by Daniel Radcliffe, with ill-disguised disdain. Mr. Griffiths and Radcliffe later worked together in London and New York stage productions of Peter Shaffer’s “Equus.”
In 2004, Mr. Griffiths found his signature role as Hector, a teacher in Alan Bennett’s play “The History Boys.” An inspiring and erudite boys’ schoolteacher who sought to inspire a love of learning, Hector also harbored a not-so-secret longing for some of his students.
“This was an absolutely enormous opportunity that I hadn’t seen for decades,” Mr. Griffiths told Canada’s National Post newspaper in 2006. “This was a new play, and nobody had ever done it before. And I was going to have the chance to create this character from the get-go, from the ground up.”
Mr. Griffiths won an Olivier, the British equivalent of the Tony Award, then took the Tony for best actor after the play came to Broadway in 2006. “The History Boys” was made into a film in 2006.
Nicholas Hytner, who directed the theatrical and movie versions of “The History Boys,” said in a statement that Mr. Griffiths’s performance was “a masterpiece of wit, delicacy, mischief and desolation, often simultaneously.”