Christopher Plummer
Russell Crowe and Anne Hathaway are among the other Hollywood figures who have honoured the Canadian actor online.
The Canadian was the oldest actor to win an Oscar – and is best known for playing Captain von Trapp opposite Julie Andrews.
"I’ve been accredited by my industry at the highest levels and that still didn’t translate to equal pay."
She slammed the decision to axe him from 'All The Money In The World'.
The unprecedented move has been described as "monumentally expensive".