Simplify the following text for a Grade 9 native English-speaking person.
Original: Its main entertainment features and holdings include Walt Disney Motion Pictures Group , Disney Music Group , Walt Disney Theatrical , Disney-ABC Television Group , Radio Disney , ESPN Inc. , Disney Interactive Media Group , Disney Consumer Products , and Marvel Entertainment .
Simplified: The Walt Disney Company , commonly nicknamed Disney , is one of the largest entertainment and media companies in the world . It was started in 1923 by Walt Disney and his brother , Roy Oliver Disney , as the Disney Brothers Cartoon Studio .