Officer Cass was an NPC, an Imperial officer onboard the Peace Moon.
A New Generation Edit
Darth Vader was with Tarkin on the Peace Moon, discussing how when Vader offered Vader's daughter Princess a chance to join Vader and rule the Galaxy, Princess spat on Vader. Vader denied being upset by this, since this meant Princess gave in to her anger. Officer Cass arrived to clean off the phlegm on Vader.
Officer Cass was later killed along with everyone else onboard the Peace Moon when Luke blew it up.