Dane Witherspoon, who was married to the 'House of Cards' actress for two years until 1988, passed away on Saturday (29.03.14) at the age of 56.
The former couple met when they co-starred on the soap opera 'Santa Barbara' together in 1984.
Actor A Martinez, who also starred on the series, announced the news on his Facebook page, according to Soap Opera Digest.
He wrote: "Dane passed this morning. People who watched Santa Barbara in its earliest days will remember him as Joe Perkins, a character to which he brought a quiet grace and deep, bittersweet sense of soul."
Robin, who was also previously married to Sean Penn for 13 years until 2010, with whom she has daughter Dylan, 22, and son Hopper, 20, got engaged to her boyfriend of two years, Ben Foster, in November.
The blonde beauty, 47, recently admitted that she found her divorces "devastating."
Robin also said her 33-year-old partner has given her a new lease of life and made her feel young again.
She added: "I know I'm almost 48, but I feel like I'm 30. I feel like I've digressed and now I'm going to live my 30s again."