Maltheist

A Maltheist is someone who believes that a God or gods exist, and that they are evil, malicious, incompetent, or otherwise causing the suffering of humanity.
 * Gnostics are semi-Maltheistic, as they believe the material world was created by an imperfect, evil sub-god named Ialdabaoth.
 * The Church of the SubGenius often has a strong maltheistic streak to its deities.
 * The fictional writings of Howard Phillips Lovecraft were maltheistic, in that the godlike alien beings he depicted were, at best, indifferent to humanity--and drawing their attention could be catastrophic.

Christianity
Fred Phelps and other similar Christians believe that God creates some people foreknowing that they will be damned and creates such people because he wants to damn them. God is also perfectly good because good is by definition what God wants. This is not maltheism in strict logics but when words are used in the human sense it comes close to maltheism.

Adapted from RationalWiki