Conscience is Blockhead's conscience who strongly dislikes him. He has gray hair and wears a white t-shirt and purple shorts. The Conscience is always bare-footed, and is always seen sitting in a chair with a lamp above him. In the first episodes there were empty bottles around the chair that still had some liquid, possibly alcohol, in them. He is the cynical voice of reason Blockhead continually ignores, and whom only Blockhead can hear. Although he appears as an old man, Blockhead has a picture of a similar looking man above his television, that is what he imagines him to look like, As explained in episode 4.
The Swain re-designed the The Conscience as seen in Episode 9.