1. As a child, Norma Jeane Baker (Marilyn Monroe) lived in an orphanage and had 11 sets of foster parents, after her mother Gladys was institutionalized.
2. She almost chose the screen name of Jean Adair before settling on Marilyn Monroe.
3. Her agent Johnny Hyde reportedly convinced her to have two plastic surgeries: reshaping the cartilage at the tip of her nose and a chin implant.
4. Although she was typecast as a dumb blonde (a persona she hated), she was actually extremely intelligent. She had an IQ of 168.
5. Although she famously sang “Diamonds Are a Girl’s Best Friend,” in reality Monroe wasn’t into expensive jewelry. All the jewelry she owned was costume, expect for a diamond ring and a strand of pearls given to her by her second husband, Joe DiMaggio.
6. She was one of the first women to own her own production company, Marilyn Monroe Productions. The company released only one movie though, The Prince and the Showgirl (1957).
7. She was an excellent cook!
8. Monroe helped change the course of Ella Fitzgerald's career by personally calling the owner of the popular Hollywood nightclub, Mocambo, and helping her get booked. Initially the club would not book Ella because she was black.
9. Monroe converted to Judaism after marrying playwright Arthur Miller.
10. During her marriage to Miller, Monroe tried to have a child (she desperately wanted to become a mother); unfortunately she suffered both an ectopic pregnancy and a miscarriage.
11. Miller wrote Monroe's role in The Misfits as a Valentine's Day gift to her. Although she hated the role, many critics consider it the best performance of her career.
12. After her breakup with Miller, Frank Sinatra gave Monroe a Maltese terrier to help her feel better. She named it Maf (short for Mafia Honey).
13. Miller’s 1964 play After the Fall is a thinly veiled portrayal of his marriage to Monroe.
14. The racy flesh-colored dress Monroe wore while singing the infamous “Happy Birthday Mr. President,” was covered with 2,500 rhinestones and was so tight that she had to be sewn into it.
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In 1999, the dress sold at auction for a $1.26 million.
15. Despite wide acclaim for her acting abilities, she was never nominated for an Academy Award. However, she did win a Golden Globe for her role as Sugar Kane in Some Like It Hot.
16. Monroe made Joe DiMaggio promise to leave flowers on her grave every week if she died before him. He kept his promise and had half-dozen red roses delivered three times a week to her crypt for 20 years.
17. She was buried in a pale apple green Pucci sheath dress.
The dress was a favorite and she was photographed in it during a press conference in Mexico City in February 1962.
18. At the height of her fame, Monroe wrote her autobiography My Story (with help from her friend screenwriter Ben Hecht). The book was not published until a decade after her death.
Facts via: The Telegraph, PBS American Masters, and Neatorama