Sam Neill thinks Robin Williams was the "saddest person" he's ever met.

Robin Williams died in August 2014

Robin Williams died in August 2014

The comedy star committed suicide in August 2014, and Sam - who worked alongside him on the 1999 movie 'Bicentennial Man' - hos now opened up about their friendship, describing Robin as the "funniest person" he ever worked with.

In his new memoir, 'Did I Ever Tell You This?', he writes: "He had fame, he was rich, people loved him, great kids - the world was his oyster. And yet I felt more sorry for him than I can express. He was the loneliest man on a lonely planet."

Sam remembers Robin - who died aged 63 - as being "inconsolably solitary, and deeply depressed".

On the other hand, the comedian had the ability to make everyone else around him laugh and smile.

Sam added: "Funny stuff just poured out of him. And everybody was in stitches, and when everybody was in stitches, you could see Robin was happy."

Meanwhile, Sam recently revealed that he's received treatment for stage-three blood cancer.

The veteran actor is now cancer-free - but Sam insisted that he isn't "afraid" to die.

He told the Guardian newspaper: "I’m not afraid to die, but it would annoy me. Because I’d really like another decade or two, you know?

"We’ve built all these lovely terraces, we’ve got these olive trees and cypresses, and I want to be around to see it all mature. And I’ve got my lovely little grandchildren. I want to see them get big.

"But as for the dying? I couldn’t care less."

Sam discusses his cancer diagnosis in his new memoir, and even feared passing away before it was released.

He wrote: "The thing is, I’m crook. Possibly dying. I may have to speed this up."