Chantho

Chantho was a female Malmooth, and presumably the last of her kind. She left the Malmooth Conglomeration and worked with Professor Yana of the Utopia Project. When Yana discovered that he was in fact the Master in Human form, he fatally wounded Chantho with a live electric cable. With her dying breath, she shot the Master, triggering his regeneration. (DW: Utopia)

To be polite, Chantho, like all Malmooth, had to say the start of her name at the beginning of each sentence, then finish with its end. For example, when Martha asked what would happen if she didn't speak that way, her reply was, "Chan-That would be rude-tho." However, she was able to overcome this with a certain degree of effort, as she demonstrated to Martha, which Martha found amusing. (DW: Utopia - deleted scene)

When Davros reminded the Doctor of the sacrifices made in his name, Chantho appeared in a flashback of those who had died. (DW: Journey's End)