Wynonna - Wynonna Earp
Inheriting a rootin' tootin' talent for weaponry from the great Wyatt Earp, Wynonna has the skills to battle her enemies. Using her wits, and a bit of humor, she fights mysterious creatures alongside her fellow Marshalls to rid her town of them for good.
Bo - Lost Girl
Poor Bo didn't know she was a Succubus until she accidentally killed her high school boyfriend, so she didn't start out a leader. She hid for many years until the light Fae found her, while under attack by dark Fae. Bo's fighting skills came in pretty handy defending the light Fae and earned her the respect and followers she needed to protect her Fae and human family.
Liv - iZombie
Okay, so Liv has to feed on brains once a month to survive. That doesn't make her any less effective as a leader. She could simply eat the brains, but she doesn't. Liv uses the memories and traits from the brains she eats to solve the mysteries of their deaths. Well, when life gives you lemons, as they say.
Clarke Griffin - The 100
Just because you're labeled a juvenile delinquent, doesn't mean you can't be a fierce leader. Look at Clarke! She may have started out as a medical apprentice, but she grew into a leader alongside Bellamy, negotiating peace and fighting armies.
Captain Kathryn Janeway - Star Trek Voyager
Captain Janeway was not only the captain of the USS Voyager, but she also fought to save her crew when they got lost in the Delta Quadrant. She never gave up, and it took her seven years to bring them all home. That takes some serious chops and stamina, and if that doesn't make her a great leader, nothing does.
Diana - V
Not all strong leaders are good, as Diana proves. She was downright evil in her alien ways, both to humans and to her own beings, but she commanded leadership. She had a presence and confidence that made those who listened to her to follow her, even if they didn't know they should fear her.