Groot is an amazing character from guardians of the galaxy. In the first movie, SPOILER ALERT, he was an adult, but sacrificed himself and blew up to save the others. Rocket, his buddy, took some of his remains, and planted him. And in the second volume, Baby Groot rose from the soil.
He is eco-friendly, ya know, being a tree and all, he is sweet, helpful, loyal, but can be a jerk sometimes, and is always ready to smoke some bad guys for his friends.