Sidney Reilly, born as Sigmund Georgievich Rosenblum in Russia in 1873, inspired Ian Fleming for his character James Bond. Called the “Ace of Spies”, he spied for four nations. He dressed well, drank a lot, was a womanizer, and lived an extravagant lifestyle. He has been described as a con-man, a charmer and a cad. He was also a killer where necessary, and at times when unnecessary.
As a spy he did get some things done, but as a rule of thumb the best spies are those that keep what they do secret. Consider, for example, member of the Culper Ring (like Abraham Woodhull), who took their involvement in spying to their death.
Reilly is attributed with some of the most daring undertakings of which is most famous his involvement in the plot to assassinate Soviet leader Lenin. The plot had failed but Reilly escaped. In 1925, he went back to Russia to help overthrow the Soviet regime but he was captured by the Soviets and executed.
One of the better fictionalized series on Sidney Reilly is Reilly, Ace of Spies. It is definitely fictionalized, but good storytelling, and great acting by Sam Neill.
For more see the book: Ace of Spies, The True Story of Sidney Reilly