Hedy Lamarr was born Hedwig Eva Maria Kiesler in Vienna, Austria-Hungary, the only child of Gertrud "Trude" Kiesler (née Lichtwitz) and Emil Kiesler. Her father was born to a Jewish family in Lemberg (now Lviv in Ukraine) and was a successful bank director. Her mother Gertrud was a pianist and Budapest native who came from an upper-class Jewish family; she had converted from Judaism to Catholicism and was described as a "practicing Christian".
In the late 1920s, Lamarr was discovered as an actress and brought to Berlin by producer Max Reinhardt. Following her training in the theater, she returned to Vienna to work in the film industry. In early 1933, at age 18, she starred in Gustav Machat?'s film, Ecstasy , which was filmed in Prague.
Lamarr went on to play a number of stage roles, including a starring one in Sissy , a play produced in Vienna, which won accolades from critics. Admirers sent roses to her dressing room and tried to get backstage to meet her.
After an early and brief film career in Czechoslovakia, she fled from her husband, a wealthy Austrian ammunition manufacturer, and secretly moved to Paris. There, she met MGM head Louis B. Mayer, who offered her a movie contract in Hollywood, where she became a film star from the late 1930s to the 1950s.
Lamarr appeared in numerous popular feature films. At the beginning of World War II, Lamarr and composer George Antheil developed a radio guidance system for Allied torpedoes, which used spread spectrum and frequency hopping technology to defeat the threat of jamming by the Axis powers. Although the US Navy did not adopt the technology until the 1960s, the principles of their work are now incorporated into modern Wi-Fi, CDMA, and Bluetooth technology, and this work led to their induction into the National Inventors Hall of Fame in 2014.
Lamarr became a naturalized citizen of the United States at age 38 on April 10, 1953. In her later years, Lamarr turned to plastic surgery to preserve the looks she was terrified of losing, but the results were disastrous.
Lamarr was married and divorced six times. She adopted a son, James, in 1941, during her second marriage to Gene Markey. She went on to have two biological children, Denise (born 1945) and Anthony (born 1947), with her third husband, actor John Loder, who also adopted James. Following her sixth and final divorce in 1965, Lamarr remained single for the last 35 years of her life.
Lamarr died in Casselberry, Florida, aged 85. Her death certificate cited three causes: heart failure, chronic valvular heart disease, and arteriosclerotic heart disease. Her son Anthony Loder took her ashes to Austria and spread them in the Vienna Woods, in accordance with her last wishes.