Felicity Smoak is a main character on CW series Arrow and a part of the Arrowverse.
Felicity is a kind-hearted, brilliant scientist, who spent her youth as a hacktivist, which she quit after her boyfriend at the time was arrested. She is arguably at genius-level, which is paired with an innate social awkwardness and tendency to delve into work rather than social engagements. This all changes when Felicity becomes a part of Team Arrow as Overwatch and forms lifelong bonds with her comrades-in-arms Green Arrow, Spartan, Black Canary and Speedy, among many others. Felicity is considered an invaluable part of the team and in many instances provides a reality-check balance to Oliver, as she is one of few who do not falter in the face of his dismay.
She was able to successfully create a single small solar device capable of powering an entire building.
It's been teased several times that she has her own company called "Smoak technologies" in the distant future. *she is fiercely loyal and dedicated to oliver and her teammates/Friends. *she is a STEM prodigy.