Zhuan Zhu
Zhuan Zhu was an assassin in the Spring and Autumn period. As Prince Guang wanted to kill King Liao of Wu and take the throne himself, Zhuan Zhu was recommended to Prince Guang by Wu Zixu. In 515 BC he managed to kill King Liao in a party with a dagger hidden in a fish. He was killed after he had completed his mission.
In folklore, the dagger he used to kill King Liao was named Yuchang, or "Fish intestines", because it was small enough to be hidden in a fish.