Comet 67p/ Churyumov-Gerasimenko has become famous as a result of the ESA Rossetta mission to orbit the comet. Thanks to this mission we know more about this comet than any other!
From the ground, the comet is not a particularly striking object. During the 2015 return, it peaked at about 11th magnitude. The image below was taken on August 13, 2015, shortly after the comet appeared from behind the Sun. At the time the comet was about magnitude 12.5 and displayed a short dust tail and a longer ion tail.
As the comet moved away from the Sun it brightened slightly and became more easily observable.