Sir Pentious has a snake-like appearance with a body color predominantly in charcoal grey. His eyes have cerise scleras with black pupils, and a mouth with sharp yellow teeth, two of which are long snake-like fangs.
His tail is black with thick yellow stripes featuring numerous cerise eyes running down the length of it. He has a black cobra hood with its front colored yellow with black corners and four cerise eye patterns spread across the center.
Sir Pentious wears a jacket in a matching charcoal grey to his skin, pinstriped with yellow, and a black bow tie with a single cerise eye in the center. Beneath the jacket is a long-sleeved yellow undershirt. He also wears black fingerless gloves with yellow dots on each knuckle and has sharp cerise claws.
He accessorizes with a large top hat in charcoal grey, which has a sizeable cerise eye in the center of it, as well as many sharp yellow teeth and a pair of goggles. The top hat blinks and changes expressions in unison with Sir Pentious.