Lamarr was born Hedwig Eva Maria Kiesler in 1914 in Vienna, Austria-Hungary, the only child of Gertrud “Trude” Kiesler (née Lichtwitz; 3 February 1894 – 27 February 1977) and Emil Kiesler (27 December 1880 – 14 February 1935). Her father was born in Lemberg and was a successful bank director. He died before the Holocaust, and later Hedy, through her influence as an actress, was able to rescue her mother from this plight. Her mother was a pianist and Budapest native who came from the “Jewish haute bourgeoisie”. Stephen Michael Shearer, a Lamarr biographer, asserts that Lamarr’s mother had converted from Judaism to Catholicism and was a “practising Christian”.  In the late 1920s, Hedy was discovered as an actress and brought to Berlin by producer Max Reinhardt. Following her training in the theater, she returned to Vienna where she began to work in the film industry, first as a script girl, and soon as an actress. In 1933 she married Friedrich Mandl, a wealthy Austrian military arms merchant. Hedy would often accompany him to business meetings where he conferred with scientists and other professionals involved in military technology. These conferences became her introduction to the field of applied science and the ground that nurtured her latent talent in the scientific field. As World War II loomed, Hedy’s acting career took her to Hollywood where she soon became a naturalized U.S. citizen.

At the beginning of the war, she was told that she could better help the war effort by using her celebrity status to sell War Bonds, which she did with great success. But she wanted to do more, particularly by using her interest in science to aid in the defeat of Nazism. This desire only intensified as Hitler continued his relentless attacks on Europe. When German submarines began torpedoing passenger liners, she said at one point, “I’ve got to invent something that will put a stop to that.” This desire would give rise to the invention for which she would become famous many years later.  In early 1933, at age 18, she starred in Gustav Machatý’s film, Ecstasy (Extase in German and Czech), which was filmed in Prague, Czechoslovakia. Lamarr’s role was that of a neglected young wife married to an indifferent older man. The film became notorious for showing Lamarr’s face in the throes of orgasm as well as close-up and brief nude scenes in which she is seen swimming and running through the woods.

Friedrich Mandl, her first husband, objected to what he felt was exploitation of his wife and “the expression on her face” during the simulated orgasm. He purportedly bought up as many copies of Ecstasy as he could find in an attempt to restrict its public viewing. In her autobiography, she insists that all sexual activity in the film was simulated, and the orgasm was achieved using “method acting reality”. The authenticity of passion was attained by the film director’s off-screen manipulation of a safety pin strategically poking her bottom. Lamarr had married Mandl at the age of 19 on 10 August 1933.  Reputed to be the third richest man in Austria, Mandl was a munitions manufacturer. In her autobiography Ecstasy and Me, Lamarr described Mandl as extremely controlling, preventing her from pursuing her acting career and keeping her a virtual prisoner, confined to their castle home, Schloss Schwarzenau. Although half-Jewish himself, Mandl had close social and business ties to the fascist governments of Italy and Nazi Germany, selling munitions to Mussolini.  Lamarr wrote that Mussolini and Hitler had attended lavish parties hosted at the Mandl home. Mandl had her accompany him to business meetings, where he conferred with scientists and other professionals involved in military technology. These conferences were her introduction to the field of applied science and the ground that nurtured her latent talent in science.  Lamarr’s marriage to Mandl eventually became unbearable, and she decided to separate herself from both him and her country. She wrote in her autobiography that she disguised herself as her maid and fled to Paris. However, rumors claimed that Lamarr persuaded Mandl to let her wear all of her jewelry for a dinner, then disappeared.

After escaping her husband, she fled to Paris in 1937 where she met Louis B. Mayer, who was scouting for talent in Europe. Mayer hired her but insisted that she change her name to Hedy Lamarr—she had been known as “the Ecstasy lady”—choosing the surname in homage to the beautiful silent film star, Barbara La Marr, who had died in 1926 from tuberculosis. Upon arriving in Hollywood in 1938, Mayer promoted her as the “world’s most beautiful woman.”  She received good reviews for her American film debut in Algiers (1938) with Charles Boyer, who asked that Lamarr be cast after meeting her at a party. In Hollywood, she was invariably cast as the archetypal glamorous seductress of exotic origins. Lamarr played opposite the era’s most popular leading men. Her many films include Boom Town (1940) with Clark Gable and Spencer Tracy, Comrade X with Gable, White Cargo (1942), Tortilla Flat (1942) with Tracy and John Garfield, H. M. Pulham, Esq. (1941) with Robert Young, and Dishonored Lady (1947). In 1941, Lamarr was cast alongside Lana Turner and Judy Garland in Ziegfeld Girl.

Lamarr made 18 films from 1940 to 1949 even though she had two children during that time (in 1945 and 1947). After leaving MGM in 1945, she enjoyed her biggest success as Delilah in Cecil B. DeMille’s Samson and Delilah, the highest-grossing film of 1949, with Victor Mature as the Biblical strongman. However, following her comedic turn opposite Bob Hope in My Favorite Spy (1951), her career went into decline. She appeared only sporadically in films after 1950, one of her last roles being that of Joan of Arc in Irwin Allen’s critically panned epic, The Story of Mankind (1957). White Cargo, one of Lamarr’s biggest hits at MGM, contains, arguably, her most memorable film quote delivered with hints of a provocative invitation: “I am Tondelayo. I make tiffin for you?” This line typifies many of Lamarr’s roles, which emphasized her beauty and sexuality but were light on lines. The lack of acting challenges bored Lamarr, and she turned to inventing to relieve her boredom.

Lamarr’s earliest inventions include an improved traffic stoplight and a tablet that would dissolve in water to create a carbonated beverage. The beverage was less than successful; Lamarr herself claimed it tasted like Alka-Seltzer.  Lamarr’s reputation as an inventor is based on her co-creation of a frequency-hopping system with George Antheil, an avant garde composer and neighbor of Lamarr in California. During World War II, Lamarr was inspired to contribute to the war effort, and focused her efforts on countering torpedoes. In her home, explains author Richard Rhodes during an interview on CBS, she devoted a room to drafting her designs for frequency-hopping.  Lamarr and Antheil discussed the fact that radio-controlled torpedoes, while important in the naval war, could easily be jammed by broadcasting interference at the frequency of the control signal, causing the torpedo to go off course. Lamarr had learned something about torpedoes during her marriage to Mandl. Lamarr and Antheil developed the idea of using frequency hopping to avoid jamming. This was achieved by using a piano roll to unpredictably change the signal sent between a control center and the torpedo at short bursts within a range of 88 frequencies in the radio-frequency spectrum (there are 88 black and white keys on a piano keyboard).

The specific code for the sequence of frequencies would be held identically by the controlling ship and in the torpedo. It would be practically impossible for the enemy to scan and jam all 88 frequencies, as computation this complex would require too much power. The frequency-hopping sequence was controlled by a player-piano mechanism, which Antheil had earlier used to score his Ballet Mécanique.  On August 11, 1942, U.S. Patent 2,292,387 was granted to Hedy Kiesler Markey, Lamarr’s married name at the time, and George Antheil. This early version of frequency hopping, although novel, soon was met with opposition from the U.S. Navy and was not adopted. The idea was not implemented in the U.S. until 1962, when it was used by U.S. military ships during a blockade of Cuba after the patent had expired. Lamarr’s work was honored in 1997, when the Electronic Frontier Foundation gave her a belated award for her contributions. In 1998, an Ottawa wireless technology developer, Wi-LAN Inc., acquired a 49% claim to the patent from Lamarr for an undisclosed amount of stock.

Lamarr’s and Antheil’s frequency-hopping idea served as a basis for modern spread-spectrum communication technology, such as Bluetooth, COFDM (used in Wi-Fi network connections), and CDMA (used in some cordless and wireless telephones). Blackwell, Martin, and Vernam’s 1920 patent seems to lay the communications groundwork for Lamarr and Antheil’s patent, which employed the techniques in the autonomous control of torpedoes.  Lamarr wanted to join the National Inventors Council, but was reportedly told by NIC member Charles F. Kettering and others that she could better help the war effort by using her celebrity status to sell War Bonds. Lamarr did participate in a war-bond selling campaign with a sailor named Eddie Rhodes. Rhodes would be in the crowd at each Lamarr appearance, and she would call him up on stage. She would briefly flirt with him before asking the audience if she should give him a kiss. The crowd would of course say yes, to which Hedy would reply that she would if enough people bought war bonds. After enough bonds were purchased, she would give Rhodes his kiss, and he would head back into the audience. Then they would head off to the next war bond rally.  Lamarr and Antheil were inducted into the Inventor’s Hall of Fame in 2014.

Lamarr became a naturalized citizen of the United States on 10 April 1953, at age 38. In 1966, she was arrested for shoplifting in Los Angeles. The charges were eventually dropped. In 1991, she was arrested on the same charge in Florida, this time for $21.48 worth of laxatives and eye drops. She pleaded “no contest” to avoid a court appearance, and in return for a promise to refrain from breaking any laws for a year, the charges were once again dropped.  According to her autobiography Ecstasy and Me (1966), while attempting to flee her husband, Friedrich Mandl, she reputedly slipped into a brothel and hid in an empty room. While her husband searched the brothel, a man entered the room and she had sex with him so she could remain unrecognized. She was finally successful in escaping when she hired a new maid who resembled her; she drugged the maid and used her uniform as a disguise to escape.  Lamarr later sued the publisher, saying that many of the anecdotes in the book, which was described by a judge as “filthy, nauseating, and revolting,” were fabricated by its ghost writer, Leo Guild. She was also sued in Federal Court by Gene Ringgold, who asserted the actress’s autobiography contained material from an article about her life which he wrote in 1965 for a magazine called Screen Facts.  The publication of her autobiography took place about a year after the accusations of shoplifting and a year after Andy Warhol’s short film Hedy (1966). The shoplifting charges coincided with a failed attempt to return to the screen in Picture Mommy Dead (1966). The role was ultimately filled by Zsa Zsa Gabor.

The 1970s was a decade of increasing seclusion for Lamarr. She was offered several scripts, television commercials, and stage projects, but none piqued her interest. In 1974, she filed an invasion of privacy lawsuit for $10 million for an unauthorized use of her name (i.e. “Hedley Lamarr” in Mel Brooks’ Blazing Saddles); the case was settled out of court. With failing eyesight, she retreated from public life and settled in Miami Beach, Florida in 1981.  For several years beginning in 1997, the boxes of CorelDRAW’s software suites were graced by a large Corel-drawn image of Lamarr. The picture won CorelDRAW’s yearly software suite cover design contest in 1996. Lamarr sued Corel for using the image without her permission. Corel countered that she did not own rights to the image. The parties reached an undisclosed settlement in 1998.  For her contribution to the motion picture industry, Hedy Lamarr has a star on the Hollywood Walk of Fame at 6247 Hollywood Blvd.  In her later years, Lamarr turned to plastic surgery to preserve the looks she was terrified of losing. Lamarr had to endure disastrous results. “She had her breasts enlarged, her cheeks raised, her lips made bigger, and much, much more,” said Anthony. “She had plastic surgery thinking it could revive her looks and her career, but it backfired and distorted her beauty.” Anthony Loder also claimed that Lamarr was addicted to pills.  Lamarr became estranged from her adopted son, James Lamarr Loder, when he was 12 years old. Their relationship ended abruptly and he moved in with another family. They did not speak again for almost 50 years. Lamarr left James Loder out of her will and he sued for control of the $3.3 million estate left by Lamarr in 2000.

Lamarr died in Casselberry, Florida on 19 January 2000, aged 85. Her death certificate cited three causes: heart failure, chronic valvular heart disease, and arteriosclerotic heart disease. Her death coincided with her daughter Denise’s 55th birthday. Her son Anthony Loder took her ashes to Austria and spread them in the Vienna Woods, in accordance with her last wishes.  Lamarr was given an honorary grave in Vienna’s Central Cemetery in 2014.