Big the Cat is a character from the Sonic the Hedgehog series.
He is the heaviest and largest non-metal character in the series. His character designer is either Yuji Uekawa, Takashi Iizuka or even Naoto Oshima
Big was sleeping in his hut one night, when he woke up and saw that his friend, Froggy, had swallowed his lucky charm; the yellow Chaos Emerald. As soon as he noticed that Froggy had grown a tail, Froggy ran off, causing Big to chase after him. After trying to catch him in Twinkle Park, and then in Ice Cap, Big was able to catch Froggy on Emerald Coast, but E-102 Gamma caught him and ran away. Seeing that, Big tried to convince the robot to give him Froggy back, but without any positive results.
Later, Big went on board the Egg Carrier and after finding Froggy once again, he fished him in one of the many water tanks on the Hot Shelter. He was then teleported by Tikal into the past for a while, so she could pass him a message, just like she did to the other characters, about Chaos. In Big’s case, he was shown just how important his “lucky charm” really was. When he got back to the present, he tried to get out of the Egg Carrier, but was caught by Doctor Eggman and Chaos 4, which then evolved to Chaos 6 when he absorbed Froggy (whose tail and Chaos Emerald had disappeared). Just then, Sonic appeared to the rescue. Big merely had to fish Froggy out of Chaos 6, leaving the rest to Sonic once he rescued his buddy. After leaving Chaos to Sonic, Big found the Tornado 2 and decided to fly home with it, crashing the plane right next to his house. However, that made the Chaos Emerald inside the Tornado 2 an easy target to Chaos when he was on a vicious rampage to gather all seven by himself. When Perfect Chaos destroyed the city of Station Square Big gave one of the seven Chaos Emeralds to Sonic so he could defeat him.