To face danger or a crisis without fear

to die for a cause in a time of crisis

To think only of one's own interests or safety when facing a crisis or dangerous situation; to be selfish in a moment of peril.

to remain steadfast in the face of danger or crisis without hesitation or concern for oneself; (literary) to face death or danger with courage and resolve

to remain calm and composed in the face of danger or crisis without losing one's head

(idiom) to be entrusted with a difficult mission or to take on a leadership role at a critical moment of danger