Monroe began working in a factory and was photographed by the Army as a promotion to show women on the assembly line contributing to the war effort. Monroe got noticed instantly and by 1945, she was the 'MMM Girl', appearing on many covers of magazines.
On July 23, 1946 she signed a contract with Twentieth Century-Fox Studios, and given the name 'Marilyn Monroe'. Her first serious acting job came in 1950 when she had a small part in 'The Asphalt Jungle". Late 1952 her role in 'Clash By Night' won rave reviews. She landed in the leading role for 'Don't Bother to Knock' in the same year.
In 1952, Marilyn began filming "Niagara" with Joseph Cotten. After her next big film, "Gentlemen Prefer Blondes", she and Jane Russell were immortalized in the wet cement in front of Mann's Chinese Theatre. She had made it big.
Monroe didn't want to be typecast as a dumb-blonde, and in 1954 she refused
to act as one in 'Pink Tights' and hence was suspended by Fox. She did
her famous ventilator scene from "The Seven Year Itch", in New York with
2000 over spectators, photographers and her husband Joe Dimaggio. 
Monroe returned to Hollywood in February 1956 and formed her own movie studio 'MM Productions'. Her first comeback film was "Bus Stop". Her next was 'The Sleeping Prince', then the rather famous "Some Like It Hot" with Jack Lemmon and Tony Curtis. The latter earned Monroe her Golden Globe. However, her next film 'Let's Make Love' flopped at the box office.
She hired Eunice Murray as housekeeper, as recommended by Dr Greenson,
her psychiatrist. Murray, calling herself a nurse, had neither the training
or credentials. It is suspected that she was a "spy" for Dr. Greenson who
continued to have more and more control over Monroe's life.
Monroe was found dead in the nude by her housekeeper early on the morning
of August 5, 1962. No one knew what had happened.