Phil, the Prince of Insufficient Light, is the ruler of Lower Heck in Scott Adams's Dilbert comic strip. He punishes people (usually Dilbert) for minor infractions not worthy of damnation in hell, such as using copier paper for the printer or stealing a chair from another cubicle (both of which Dilbert has done). He also serves as manager of limbo, which in the strip is a subsidiary of Heck. He is the Pointy-Haired Boss's younger brother, though this has been mentioned only twice, most recently in a strip involving Phil outsourcing the housing of sinners who partake of carbohydrates to the PHB's workers' cubicles.
Originally, Adams planned to have Satan, the Prince of Darkness, become a regular member of the Dilbert cast, but eventually softened the character after suggestions by his editor. Instead of a pitchfork, Phil carries an enormous spoon, which Dilbert is once condemned to wax and "darns people to heck" instead of damning them to hell.
Often, the punishments Phil gives are meant to annoy the person rather than outright torment them. An example would be forcing Dilbert to sit at the female receptionist's desk and endure the stale wit of his co-workers, who make bad jokes centering around the idea that Dilbert is the female receptionist.
Phil has been inconsistently drawn throughout the series, which Adams mentioned several times in Seven Years of Highly Defective People. Sometimes Phil has a pointed tail, carries a pitchfork, or (most commonly) wears a cape because Adams forgets that Phil isn't supposed to be wearing them.