Skull CupSkt., kapala
Many Tibetan deities and dignitaries, including several Dharmapala's, Dakinis, and Mahasiddhas, are depicted or described as carrying a a cup made from the upper part of a human skull. In some cases they are simply carried, either empty or filled and usually in the left hand; in other cases the deity in question is shown drinking from one that is filled with blood. These variations occur also within Hindu traditions where skull cups are often shown with the deities Durga, Kali, and Shiva; to name but a few.
There are several Sanskrit and Tibetan terms for these skull cups, depending on the type of skull used in their preparation, on being empty or filled and on the material they are filled with (mamsakapala, khrag-zor); and some of these categories are also depicted differently.
Many skull-cups, especially Tibetan ones, are elaborately designed, engraved, given silver rim linings (sometimes many small skulls) or have specifically made standards (see this image) and covering lids. Although both the Indian and Tibetan traditions always speak of the kapala as merely a symbolic and iconographic device representing the destruction of demonic (or human) enemies of the religion, it is quite certain that (human) blood was actually drunk from such cups and/or (human sacrificial) flesh actually eaten. These cups are probably the best known and most often depicted / used among the Charnel Ground Ornaments and Implements.