The Mariner 2 space probe completed the first-ever flyby of Venus.

Mariner 2 was launched from Cape Canaveral earlier that year on August 27, after the Mariner 1 probe veered off course and was destroyed. The Atlas rocket used to launch both probes proved problematic for the Mariner 2 and sent it off its course, but fortunately, it was able to be corrected mid-flight.

Source