A Steven Spielberg film starring Meryl Streep as his mother, which is based on her time as head of the newspaper, was released on December 22 - just two days before his death.
His death came six days after the film's premiere in Washington DC.
Graham was a prominent lawyer at the Williams & Connolly firm in Washington DC in the 1970s before he moved to Los Angeles.
He later taught trial law the University of California at Los Angeles.
He founded and ran investment firm Graham Partners for 20 years before dissolving the business in 2001.
Graham then devoted himself to philanthropic activities, many of which remained anonymous.
His grandfather Eugene Meyer bought the Post at a bankruptcy auction in 1933.
Katharine, who was Meyer's daughter, oversaw the paper through some of its most important stories, including the Watergate scandal.
The recently released film recounts the behind-the-scenes story of the 1971 publication of the Pentagon Papers, which exposed the lies behind US involvement in the Vietnam War.
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
OR IF YOU NEED TO TALK TO SOMEONE ELSE:
• LIFELINE: 0800 543 354 (available 24/7)
• SUICIDE CRISIS HELPLINE: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• YOUTHLINE: 0800 376 633
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757
