Colossal Boy

Colossal Boy real name Gim Allon, is a member of the Legion of Super-Heroes who can increase his size and strength to gigantic levels. The Original Gim Allon was born the only son to Wynn and Marte Allon of Earth. He was raised in a patriotic and Jewish family. As a young man, Gim enrolled in the Science Police Training Academy to become a member of the Science Police. While on vacation on Mars with fellow cadet and childhood friend Gigi Cusimano, a strange meteor crashed into the soil near him. The meteor's radiation altered his body's RNA, giving him the power to grow to giant sizes at will. On the Threeboot Earth-Prime reality, Gim Allon was from Earth but has different ancestry. He was born to a race of giants and had a genetic mutation which allowed him to shrink to a 6' height. As a Legionnaire, Gim has completed personal combat training and wears the Legion flight ring to fly. The ring also serves as a communication and projection tool. With his additional combat training from his studies with the Science Police, he is one of the most skilled hand-to-hand combatants in the LSH and familiar with law protocol.

I remember when I was a kid, I pretended to be Colossal Boy and play with my action figures as if they were small humans, ha. 
This background is from the concept art of Mass Effect 3, it's titled Thessia and done by artist Kathryn aka Fluidity. I went over it and changed it enough so it fits the 2D animation style better.