【Brave】 , 【courageous】 , 【unafraid】 , 【fearless】 , intrepid,  【valiant】 , 【valorous】 , 【dauntless】 , 【undaunted】 , 【doughty】 , bold,  【audacious】 are comparable when they mean having or showing no fear when faced with something dangerous, difficult, or unknown.

【Brave】 usually indicates lack of fear in alarming or difficult circumstances rather than a temperamental liking for danger.

【Courageous】  implies stouthearted resolution in contemplating or facing danger and may suggest a temperamental readiness to meet dangers or difficulties.

【Unafraid】 simply indicates lack of fright or fear whether because of a 【courageous】 nature or because no cause for fear is present.

【Fearless】 may indicate lack of fear, or it may be more positive and suggest undismayed resolution.

【Intrepid 】 suggests either daring in meeting danger or fortitude in enduring it.

【Valiant】 suggests resolute courage and fortitude whether in facing danger or in attaining some end.

【Valorous】 suggests illustrious bravery and, more often than 【valiant】 , qualifies accomplishments rather than persons or their exertions; thus, one might refer to the 【valorous】 deeds of a 【valiant】 band of knights.

【Dauntless】 emphasizes determination, resolution, and fearlessness despite danger or difficulty.

【Undaunted】 indicates continued courage and resolution after danger, hardship, or defeat.

【Doughty】 combines the implications of formidable, sturdy, and 【brave】 but may have an archaic or humorous suggestion.

【Bold 】 may indicate a forward or defiant tendency to thrust oneself into difficult or dangerous situations.

When used of immaterial things (as plans, experiments, or deeds) bold suggests a disregard for danger, risk, or convention.

【Audacious】  implies spirited and sometimes reckless daring.