Board Thread:General Discussion/@comment-30644093-20170427085354/@comment-25375217-20170429031512

KnocknickKnock wrote: Emma has never defeated Regina last time checked. She didn't kill her or physically subdue, but she defeated her (dictionary definition: to overcome in a contest, election, battle, etc.; prevail over; vanquish) multiple times throughout Season 1, such as by being elected sheriff or, most importantly, breaking the Dark Curse.

Cruella and the Dark Ones are the most comparable defeats, though.