The Robot Assassins are one of Aku's many Robotic warriors.
The Robot Assassins first appeared in Jack and the Warrior Woman where they ambush Jack while he was looking for a way to travel back in time. They were later destroyed by Jack and Ikra, possibly to make sure that Jack did not find out that it was Aku in disguise.
They later appear in Jack in Egypt with new garments, looking for the Minions of Set along with Aku. After Aku opens their crypt, they are all destroyed by the Minions within seconds, demonstrating their speed and skill.
Due to the Past Aku's destruction, it is most likely that they wear erased from existence.