An exotic dancer whose seductive moves melted even the hardest of hearts, the mysterious Mata Hari was the toast of high Parisian society in 1905, mixing with many important high-ranking military men and politicians in Europe. But unknown to her suitors, Mata Hari was actually the stage name of Dutch-born Margaretha Geertruida Zelle, a double agent who claimed to spy for the French during World War I, but was in fact spying for Germany.

A man of arts and letters who enjoyed popularity among 18th century high society, John André was an undercover British army officer based in Philadelphia and New York during the American Revolutionary War. He convinced American General Benedict Arnold to surrender his West Point fort to the British for £20,000 pounds. However, on his way to meet Arnold, André was captured, found guilty of being in America "under a feigned name and in a disguised habit" and hanged in 1779.

Although she was hardly pretty, 17-year-old Belle Boyd had the finest looking ankles in town -- and used them to her advantage as she charmed important military secrets out of Union officers who stayed at her hotel. For her contributions to the Confederate cause, she was awarded the Southern Cross of Honor. She was imprisoned three times, but was set free. After the war, she toured the country giving dramatic, colourful lectures about her life as a Civil War spy.

Better known in history as the world's most notorious womaniser, Casanova was a well-educated, well-travelled gentleman who moved easily within the high society in 18th century Venice. For a while, he supposedly spied for King Louis XV of France, and later worked for the Venetian Inquisitors of State, gathering domestic intelligence on everyday affairs such as religion, moral misadventures and commerce.

"I only regret that I have but one life to lose for my country." Best remembered for his last words before he was hanged by the British, Nathan Hale is considered to be America's first spy during the American Revolutionary War in 1775. During the Battle of Long Island, Hale volunteered to spy on the British, disguising himself as a Dutch teacher as he made his way to New York. He was later captured after he was tricked into revealing his cover.