Tomboyish Baseball Cap

Anime & Manga

 * One of Makoto's outfits in the Sailor Moon nineties anime had her wearing a baseball hat. Fittingly, she's the Tomboy with a Girly Streak of the Inner Senshi.

Western Animation

 * An aversion in Recess where Spinelli, although she is a tomboy, wears a ski cap rather than a baseball hat.
 * The Loud House: Lana Loud always wears a red baseball cap, backwards.