Sludge Vohaul is a villain of the far future. He was the leader of the Sariens, and later held Roger Wilco prisoner. Roger Wilco sent out two messages via bottle which talked about his troubles with the Sariens and Sludge Vohaul. These messages were discovered by Rosella. Roger Wilco talked about him when he was trapped with Rosella and Graham playing cards.
Rosella and Graham (and even Mordack and Lolotte) would go onto meet Sludge Vohaual they challenged each other to board games. Rosella and Graham would sometimes give advice on how to play various board games, to help defeat Sludge Vohaul.
Someone on Sludge Vohaul's base wrote graffiti claiming Graham cross-dressed.