Rudolf Roessler (Rößler) (November 22, 1897 – December 11, 1958) was a German refugee who had moved to Switzerland in 1933, and was the proprietor of a small publishing firm in Switzerland, Vita Novi.
During World War II, Roessler ran the Lucy spy ring, an anti-Nazi Soviet espionage operation that was headquartered in Switzerland.
Roessler was able to provide intelligence about German operations and intentions on the Eastern Front, usually within a day of operational decisions being made.
Later in the war, Roessler was able to provide the Soviet Union with intelligence on the V1 and V-2 missiles.