The Omen

The Omen is a spirit of death and is one of the supporting villains from the fifth and final season of Samurai Jack.

Overview
He appears to resemble a black silhouette of an armored samurai with glowing green eyes (he appears to be slim in his silhouette form, but was actually large and bulky when exiting his horse). Whenever he appears, he would be surrounded by green fog which could mean the people what Jack was suppose to save were dead and usually stalks him due to his failures. He has no visible face and has a noose located around his neck. In Episode XCVI, Jack agrees to join with him after he originally failed to save the green furry aliens. In XCVII, The Omen warns Ashi not to step further and was forced to watch Jack to commit a seppuku, after Ashi calls Jack that hope is still alive, The Omen has enough and begins to confront Ashi, but Jack refuses to kill himself, so he instead slays him.

It is unknown if the Omen would exist without Aku's tyranny.