He won the Tony playing a brilliant teacher, but the world knows him as the uncle who locked a kid under the stairs.
Sign language was his first language. Both parents were deaf, his father fought in pubs for money, and nobody in Thornaby-on-Tees was mapping out a career in Shakespeare for him. He studied drama over his father's objections, then got spotted by Trevor Nunn on a BBC monitor and landed at the Royal Shakespeare Company in 1975.
The cult following came from Withnail and I in 1987, where he played Uncle Monty with a camp intensity that turned a modest British comedy into a drinking-game phenomenon. The global fame came later, five films as Vernon Dursley, the most loathsome uncle in children's fiction.
Two continents handed him their top theatre prize for the same role. Alan Bennett's The History Boys opened at the National Theatre in 2004, and Griffiths played Hector, the charismatic, complicated schoolteacher who can't keep his hands to himself. Sell-out audiences, a Broadway transfer with 185 performances at the Broadhurst, an Olivier, a Tony, and a BAFTA nomination for the film version.
He took his stage work seriously enough to stop shows and eject audience members for ringing phones, across at least three separate incidents. On Broadway in 2006, he threatened to walk off entirely. The audiences always applauded.
Radiation therapy at eight years old changed his body permanently. Doctors treated him for being too thin by irradiating his pituitary gland, a 1950s medical decision that wrecked his metabolism and made him obese for the rest of his life. He turned the body into a career, playing warmth, menace, and absurdity in parts that needed physical presence.
Daniel Radcliffe called him a mentor. Griffiths was there for Radcliffe's first shot as Harry Potter in August 2000, then guided him through his stage debut in Equus seven years later. Fiona Shaw called him 'a philosopher clown' who would hold up Potter shoots to finish a joke.
Tributes came quickly after his death. Daniel Radcliffe described Griffiths as present for 'two of the most important moments of my career' and was among the mourners at the funeral service at Holy Trinity Church in Stratford-upon-Avon; Griffiths was later interred at St Mary The Virgin Churchyard in Bearley, Warwickshire. His agent Simon Beresford called him 'one of our greatest and best-loved actors.'