Molly

Molly hails from Cascade, a planet with an empire throughout space made by ruthlessly attacking and conquering other worlds, was at war with the Metarex and various other species throughout the galaxy long before the Metarex's transformation into cyborgs, judging by how the enemies of Cosmo's people used the same type of aircraft in battle Molly's people used. As a result of this, the Metarex took the Planet Egg from Cascade after their transformation, reducing the planet to a lifeless and literally broken world because of Cascade having attacked Green Gate. For generations afterward, Molly's people continued to fight the Metarex as the Resistance, their numbers becoming fewer and fewer all the time. Molly was fighting against the Metarex when she met Shadow, who she believed would help save them from the Metarex.

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However, she was betrayed by her comrades and when Leon told her to leave him and the rest of the resistance to finish her life's mission, she thought of his words and, driven by grief, rushed at the Metarex mothership led by Pale Bayleaf with her guns blazing. The Metarex fleet then fired their weapons on Molly and Shadow rushed to her cockpit, and she locked crying eyes with him before her fighter was destroyed and she was killed.

(Source: Sonic Wiki)