Viking 1
Viking 1 was the first of two spacecraft (along with "Viking 2") sent to Mars as part of NASA's Viking program. On July 20, 1976, it became the second spacecraft to soft-land on Mars, and the first soft lander to successfully perform its mission. (The first spacecraft to soft-land on Mars was the Soviet Union's Mars 3 on December 2, 1971, which stopped transmitting after 14.5 seconds.) "Viking 1" held the record for the longest Mars surface mission of days (over 6¼ years) or Martian solar days, until that record was broken by "Opportunity" on May 19, 2010.
Venera 2MV-1 No.2
Venera 2MV-1 No.2, also known as Sputnik 20 in the Western world, was a Soviet spacecraft, which was launched in 1962 as part of the Venera programme, and was intended to become the first spacecraft to land on Venus. Due to a problem with its upper stage it failed to leave low Earth orbit, and reentered the atmosphere a few days later. It was the second of two Venera 2MV-1 spacecraft, both of which failed to leave Earth orbit. The previous mission, Venera 2MV-1 No.1, was launched several days earlier.