Notes:

In the French dub of Guardians of the Galaxy, Groot’s only sentence is “Je s’appelle Groot.” (an incorrect version of “Je m’appelle Groot.”, meaning “My name is Groot.”), which is here combined with the #JeSuisCharlie (“I am Charlie”) hashtag used to mention the event on social networks.

Uncaptioned picture: http://p1xer.deviantart.com/art/Guardians-Of-The-Galaxy-Groot-472679449
Captioned picture (first known occurrence): https://twitter.com/Qbe_Root/status/552928003307888642