General synonyms:
* Courageous
* Bold
* Valiant
* Daring
* Fearless
* Intrepid
* Audacious
* Heroic
* Gallant
* Stalwart
* Strong
* Resolute
* Determined
Synonyms emphasizing different aspects of bravery:
* Self-assured: Confident in one's abilities.
* Unflinching: Not backing down from challenges.
* Tenacious: Determined to achieve a goal.
* Gritty: Showing perseverance and resilience.
* Undeterred: Not discouraged by obstacles.
* Spirited: Filled with energy and enthusiasm.
* Unwavering: Steadfast and unwavering in one's convictions.
* Stalwart: Strong and reliable.
* Unyielding: Firm and refusing to give in.
More informal synonyms:
* Gutsy
* Tough
* Game
* Spirited
The best synonym to use will depend on the specific situation and the nuance you want to convey.