Emma Russell in Godzilla: King of the Monsters

In 2019’s Godzilla: King of the Monsters, Vera Farmiga’s Dr. Emma Russell initially appeared as a well-meaning scientist who is forced against her will to aid Alan Jonah’s (Charles Dance) Eco-Terrorist goals in forcibly releasing the Titans contained by Monarch.
But when she had a chance to leave Jonah’s side, Dr. Russell instead picked up the detonator and frees Ghidorah from its icy prison herself, revealing that she was actually the mole inside Monarch aiding Jonah’s forces for quite some time.