Basically an perfect girl. Someone who cares for others heaps more than herself and is usually super nice. Ellen's are usually mind-blowingly gorgeous although she's insecure and cannot see it. Ellen's are sassy and know how to pick a fight, but also know how to keep a conversation going with an best friend.
If you find an Ellen, stick with her. There's no one else like her.
Person 1: Woah, who's that girl? She's fucking awesome.
Person 2: She's obviously an Ellen. She's perfect.