The son of Robin Williams has paid tribute to the beloved actor and comedian on what would have been his 70th birthday.

Williams, star of films including Mrs Doubtfire and Good Will Hunting, took his own life in 2014 aged 63.

After his death, he was diagnosed with Lewy body dementia (LBD), which his wife Susan Schneider described as “the terrorist inside my husband’s brain”.

Williams’s eldest son, 38-year-old Zak, shared a tribute to his father on Instagram on Wednesday.

“Dad, on what would be your 70th birthday, I would want you to know that your incredible spirit lives within us,” he wrote alongside a black-and-white picture of the star.

“Our family will be celebrating you and your memory today. We miss you and love you always!”

Zak, a mental health advocate, also appeared on podcast The Genius Life to discuss his father’s death, including the “frustration” he saw over the actor’s misdiagnosis of Parkinson’s disease.

“What he was going through didn’t match one to one (with what) many Parkinson’s patients experience,” he said. “So, I think that was hard for him.”

Zak added: “There was a focus issue that frustrated him, there were issues associated with how he felt and also from a neurological perspective he didn’t feel great. He was very uncomfortable.”