Rainbow Dash from Friendship is Magic. Widely-accepted Fannon understanding that she is a lesbian in general. I found some interesting info about Rainbow Dash over the question is Rainbow Dash a Lesbian? 
Here are the texts about it: Just because dash has rainbow hair doesn’t make her a lesbian.
There is little to go on for the mane 6’s sexuality. Other than twilight and flash in EQG they don’t have much romance going on. Canonically, they don’t really discuss romance. The show only has a handful of canon couples: shining armor and princess cadence, all the mane 6’s parents, and mr. and mrs. cake.
Occasionally the really popular ships get Easter eggs or references in the show (fluttershy and discord, and rainbow dash and Soarin, ← my favorite.)
In a show with 75% female characters, a lot of the fans like lesbian pairings; it’s just more likely to happen, and M/M pairings are relatively rare.
There’s not really any indisputable proof that dash is a lesbian, nor any unquestionable proof that she’s straight. It’s all up to theory and speculation; Hasbro has always liked to leave shipping up to the fans. Confirming one popular ship would destroy the dozens of others it clashes with and make a lot of people mad. So the mane 6 are essentially single until further notice. But that doesn’t stop people from making cute fanart of them.
Here are my thoughts about if There’s not really any indisputable proof that dash is a lesbian, nor any unquestionable proof that she’s straight. I don't know if this info has changed but it makes sense to me. Someone had this comment: Rainbow Dash is infact lesbian, she is the reputation for gays and lesbians.
Here is my reply about the comment it's basically the person believing that about the character. Not really a fact about Rainbow Dash. I have never view Rainbow Dash as a lesbian at all. The ideas thinking Rainbow Dash is a lesbian always always made me say those words: What the frick. 
Don't worry other Fandoms are the same way. Every Character gets that treatment one way or another. Judging their personality is the name of the game. Just like other characters. Kodi from Balto 3 Wings of Change is example of that.