Matilda (Lost in Time)

Matilda was a lady-in-waiting to Lady Jane Grey during her nine day reign.

Biography
Matilda plotted to kill Jane so that, rather than being executed quietly like an average traitor, she would die a martyr. However, her plan was foiled by Rani, who had seen her with a messenger, and woke Lady Jane with her shouts. (SJA: Lost in Time)