Barclays is the official sponsor for the premier league
The main sponsor of Blackburn Rovers in 2009 was Crown Paints.
An official sponsor of an event or organization contributes money or other assets to the organizations or organizers of the event usually in exchange for the right to advertise its connection to the event or organization. For example a sports shoe company might become an official sponsor for an athletic event or athletic organization.
Bridgestone was the official sponser of Super Bowl 33.