What is the feminine form of heroine?

In English there are no masculine or feminine forms. English uses gender specific nouns for male or female.

The gender specific noun for a female who is admired for courage or outstanding achievements is heroine.

The corresponding gender specific noun for a male is hero.

As society changes, many gender specific nouns for females are being supplanted by using gender specific nouns for males as common gender nouns (gender neutral nouns). The noun 'hero' can be used for a male or a female.

Heroine is already female form. A heroine is a female hero. The masculine is hero, whereas the feminine is heroine.