Barbas (or Marbas) is a demon described in the Ars Goetia. He is described as the Great President of Hell governing thirty-six legions of demons. He answers truly on hidden or secret things, causes and heals diseases, teaches mechanical arts, and changes men into other shapes. He is depicted as a great lion that, under the conjurer's request, changes shape into a man.
An incubus (nominal form constructed from the Latin verb, incubo, incubare, or "to lie upon") is a demon in male form who lies upon women, in order to have sexual intercourse with them. An incubus may pursue sexual relations with a woman in order to father a child, as in the legend of Merlin. The first known incubus was Lilu, mentioned in Akkadian documents of 2400 BC | by Russian artist Konstantin Makovskiy
Succubus is a female demon or supernatural being appearing in dreams, who takes the form of a human woman in order to seduce men, usually through sexual intercourse. The male counterpart is the incubus. Religious traditions hold that repeated intercourse with a succubus may result in the deterioration of health or even death.