Date: 20 May 1961
Venera 1 is presumed to be first spacecraft to fly by Venus, though communication with Earth had been lost before it arrived.
The Soviet Union intended Venera 1 to crash into Venus. It succeeded in being the first Venus probe to leave Earth orbit, but contact was lost 7 days later. Since the Soviets were unable to command the spacecraft to perform a needed course correction, it is presumed to have flown by Venus at a distance of about 100,000 km (62,000 miles).
Image Credit: NASA