The Opportunity Rover is a mars rover that has been active since 2004. It was launched on July 7th 2003. It landed on the planet on January 25th 2004, three weeks after its twin the Spirit Rover.
So far, the Rover is still active as of June 14th 2017. (possibly outdated) The rover has gone over its planned uptime by 13+ years.
Notable things this rover has done:
It has found places where water once was. Multiple meteors with very important data have been found by the rovem it has allowed advancements to the discovery of life and future life on Mars.
Pictures taken by Opportunity
A Collection of pictures showing data collected by Opportunity