The Philae landers crash landing on Comet Churyumov–Gerasimenko (comet 67P) is actually the 3rd spacecraft landing on a comet, as asteroids and comets are from the same family of objects - comets are just active asteroids.
1st asteroid landing - NEAR Shoemaker spacecraft and asteroid Eros
In 2001, after NASA's NEAR spacecraft intensely studied the near-earth asteroid Eros for more than a year from orbit, mission controllers decided to try and land the spacecraft. Although it wasn't designed for landing, NEAR successfully touched down, setting the record as the first to successfully land on an asteroid.
Asteroids: Formation, Discovery and Exploration
2nd asteroid landing - Hayabusa and asteroid 25143 Itokawa
Both Hayabusa and MINERVA experienced complications during landing attempts, Hayabusa landed on the asteroid and sucked a small amount of debris into a sample container. MINERVA probably drifted off into space instead of landing.
Missions to Asteroids - Hayabusa
3rd asteroid landing - Rosetta missions Philae spacecraft and asteroid 67P
This is the first image ESA released taken by Philae from the comet. It shows one of the lander’s legs settled at the base of a rocky comet cliff.
The Philae Spacecraft Landed in the Shadow of the Comet’s Cliff