flag carrier

Noun

 * 1) A person carrying a standard or flag, usually at sporting events and parades, previously on the battlefield.
 * 2)  A transportation company, such as a shipping or airline company, that is registered in a given state
 * 3)  A strong supporter of a cause, or perhaps the strongest and most visible supporter of said cause.
 * "Bill was the flag carrier of the movement to improve inner city education."
 * 1)  A national airline (typically having the flag, or other national insignia, on the tail)
 * 2)  An aircraft carrier serving as a flagship
 * 1)  An aircraft carrier serving as a flagship