On screen, he played Billy Zane’s valet and bodyguard, Spicer Lovejoy, in James Cameron’s 1997 blockbuster Titanic and also gained prominence for roles such as photographer Keith Jennings in the 1976 horror film The Omen.
Warner died on Sunday at Denville Hall, a care home for those in the entertainment industry.
A statement from his family said: “He will be missed hugely by us, his family and friends, and remembered as a kind-hearted, generous and compassionate man, partner and father whose legacy of extraordinary work has touched the lives of so many over the years. We are heartbroken.
“He is survived by his beloved partner Lisa Bowerman, his much-loved son Luke and daughter in-law Sarah, his good friend Jane Spencer Prior, his first wife Harriet Evans and his many gold dust friends.”
Born in Manchester in June 1941 and educated in Leamington Spa, Warwickshire, Warner took his first steps into acting by enrolling at the Royal Academy of Dramatic Art (Rada) in London.
It was his role in the 1966 film Morgan: A Suitable Case For Treatment, in which he starred alongside Dame Vanessa Redgrave, that earned him a leading actor Bafta nomination.
His role in 1980s series Masada, which was fronted by Peter O’Toole and saw Warner playing Roman politician Pomponius Falco, earned him an Emmy.
Amid his success, Warner suffered chronic stage fright brought on by the skin condition psoriasis, and prioritised TV and film parts over theatre.
But in 2001, he returned to the stage after nearly 30 years to play Andrew Undershaft in a Broadway revival of George Bernard Shaw’s Major Barbara.
In 2014 he was among the cast of BBC Radio 4’s The Once And Future King, a series based on and adapted from TH White’s collection of fantasy novels by dramatist Brian Sibley.
Warner played Merlyn and told the BBC at the time: “Well, if you’re asked to play Merlyn on radio drama for the BBC, I certainly would not say no.
“It’s just such a wonderful character. But the great bonus is with audio… each individual can just picture for themselves, that’s the magic of radio.”
In later years he starred in films You, Me And Him and also featured in 2018’s Mary Poppins Returns as retired naval officer Admiral Boom, who was portrayed by Reginald Owen in the original film.
Warner also had an extensive list of theatre credits, having been a part of the Royal Shakespeare Company (RSC) which saw him star in productions of The Tempest, Julius Caesar and Henry VI.
He is survived by his partner Lisa Bowerman, his son Luke and daughter-in-law Sarah.