Tess

Tess was a woman from the Iron Islands and a mistress of Lord Dalton Greyjoy.

Biography
After the end of the Dance of the Dragons, Lord Dalton continued his raiding. One night, while he was sleeping, Tess slit his throat.

In the books
In the A Song of Ice and Fire novels, Tess' story is the same, but it is also mentioned that she was from Fair Isle and that she jumped to her death in the Sunset Sea after killing Dalton.