SurveyMonkey chief executive Dave Goldberg, husband of Facebook chief operating officer Sheryl Sandberg, has died aged 47, his brother wrote in a Facebook post.
“It’s with incredible shock and sadness that I’m letting our friends and family know that my amazing brother, Dave Goldberg, beloved husband of Sheryl Sandberg, father of two wonderful children, and son of Paula Goldberg, passed away suddenly last night,” Robert Goldberg wrote.
Goldberg was known for his low-key demeanour and the grace and good humour with which he handled being married to one of the nation's most recognisable executives.
In her book Lean In, Ms Sandberg attributed much of her own success to her marriage to Goldberg, who she said supported her career decisions and shared equally in the work of raising their young children.
The two married in 2004.
Tributes to Goldberg poured in over social media from friends and other executives, including Facebook chief Mark Zuckerberg, who called Goldberg "an amazing person".
Salesforce chief executive Marc Benioff tweeted: "Kindest, most generous, loving father, loyal husband, great CEO and sweetest friend."
"May his memory be a blessing."
Television and movie writer John Quaintance said on Facebook Goldberg was the first person to encourage him to write professionally, changing the course of his career.
Goldberg was also the first person Mr Quaintance met who owned a Blackberry device.
"I rolled my eyes at the idea that people were ever going to need to read their emails away from the office," he wrote.
Goldberg joined SurveyMonkey, which helps organisations conduct surveys, in 2009.
Valued at $2 billion, SurveyMonkey is backed by Bain Capital Ventures, Google Ventures, Tiger Global and others.
The family did not disclose the cause of death.