Mare Do Well is masked hero who appeared on the animated TV series My Little Pony: Friendship is Magic in the episode "The Mysterious Mare Do Well".
Depiction in the series
Mare Do Well is the hero who is intended to teach Rainbow Dash about humility. As Rainbow Dash signs autographs for a line of waiting fillies, a plummeting Twinkling Balloon carrying a screaming mare gives Rainbow Dash another chance to perform a feat of heroism. Before she can get to the balloon, however, a mysterious pony in a mask and cape appears and saves the panicking pilot, leaving Rainbow to crash into the deflated balloon. The heroic pony vanishes as quickly as she came and the mayor declares her to be Mare Do Well, Ponyville's newest hero. The crowd cheers - except for Rainbow Dash, who bitterly snubs the new hero.
Things quickly become worse for Rainbow Dash as Mare Do Well outperforms her in every regard. When a carriage filled with tourists goes flying down the steep road, Rainbow flubs the rescue whereas Mare Do Well effortlessly stops the carriage with her superior physical strength. A construction site devolves into pandemonium as a haywire crane and a collapsing structure put the workers in danger, and although Rainbow Dash manages to rescue one colt, Mare Do Well saves four in the same span of time, displaying an uncanny level of prediction. A leaky hydroelectric dam is easily plugged by Rainbow Dash, only to completely burst when she stops to compliment herself, leaving Mare Do Well to not only rescue Dash, but use unicorn magic to single-hoofedly repair the dam. Rainbow Dash's frustrations are only increased when, as she shows off her ability to fly, unlike Mare Do Well, the caped crusader herself flies by as well, now sporting pegasus wings.