Crusader (noun)

1. A person who is on a crusade, a military expedition to recover the Holy Land.
2. A person who fights for a cause or belief.
3. A person who is determined to bring about a change.

Origin:

From latin crux, meaning cross, and the old french word croisade, meaning a military expedition.

Examples:

1. The crusaders marched to the Holy Land to reclaim it from the Muslims.
2. She was a crusader for women's rights.
3. He was a crusader for environmental protection.
4. The crusaders of the civil rights movement fought for equality.
5. The crusader"s goal was to bring about a change in the government"s policy.