Cassandra Rubens Charon (also known as Catherine) is a character from Fire Emblem: Three Houses. She teaches at the Officers Academy and is one of the Knights of Seiros. As an instructor at the Academy, she offers lessons in Swords and Brawling. She hails from the Holy Kingdom of Faerghus and was once known as Lady Cassandra, a noblewoman of House Charon. She possesses a major Crest of Charon. She is 27 years old at the start of the game.
Catherine is an alumnus of the Garreg Mach Monastery Officers Academy. She is a fearsome swordswoman who wields Thunderbrand, one of the legendary weapons known as the Heroes' Relics, and is loyal to Archbishop Rhea.
Catherine was born to House Charon in the Holy Kingdom of Faerghus. When she was still a student at the Officers Academy, she and her classmates were tasked with killing monsters, but they were ambushed and she nearly died. Rhea saved her and nursed her back to health. She was implicated in a plot to kill the king and had to flee the kingdom, becoming an outlaw. She sought safety at Garreg Mach Monastery and Rhea took her in.
She and Lysithea both have a Crest of Charon, implying they are related.