The first to use the name Quasar is Wendell Vaughn, a Bronze Age superhero formerly known as Marvel Boy before an ancient cosmic entity known as Eon bestows upon him the Quantum Bands (along with the modest title Protector of the Universe). He has held the moniker of Quasar for longer than any other character and is likely the version that most longtime comic book fans picture in their minds when they hear it.
In the 2007 event series “Annihilation,” the bands are thrust into the hands of Phyla-Vell, an already powerful Kree-Eternal heroine who was then known as Captain Marvel. MCU fans may remember a young character named Phyla (Kai Zen) in “Guardians of the Galaxy Vol. 3,” though all we know about her so far is that she’s a “Star Child” born from the High Evolutionary’s (Chukwudi Iwuji) horrific experiments.
The third main Quasar is Avril Kincaid, a human SHIELD agent who is given the Quantum Bands by a retired Wendell Vaughn. She has essentially served as the modern Quasar alongside a revitalized Vaughn, and their ability to swap places with each other using the Quantum Bands seems to have inspired the identical plot device in “The Marvels.” If Marvel Studios were to produce a “Quasar” project, there’s a strong argument to be made that Kincaid would be the lead protagonist.