The commander of an ancient Martian force at war with the Dol'drm, whose decision to destroy their world reshaped the solar system.
Cassell, played by Saffron Burrows, is the Martian commander in Valles Marineris. After a solar storm throws the Enterprise back 65 million years, the ship is captured by Martians fighting a war against the insect-like Dol'drm, whose world lies between Mars and Jupiter. Christopher Pike offers to help end the conflict peacefully.
When Cassell learns that Mars will become a barren wasteland, she takes the Enterprise's antimatter fuel cell to use as a weapon. Pike chooses not to stop her at the last moment, and the destruction of the Dol'drm planet helps set Mars on its path to desolation.