Ellie has bright green eyes, dark auburn hair, fair skin with freckles, a scar bisecting her right eyebrow, and she is lithe. She is 19 years old, 5'5 feet tall, and has a tattoo of a fern and a moth on her right arm, which also covers up the bite she got from an infected.

She likes to collect trading cards from the Savage Starlight comic book series. Even though they aren't worth anything, it's a hobby that gives her comfort.

Ellie hides her immunity from everyone, except Joel.