Some books on demonology, like Arbatel de Magia Verum and The Lesser Key of Solomon (or Lemegeton) assert that all demons has his/her own signature collectively called seal of the demons, and that sign the acts of diabolical pacts with them.

These "seals" (not seals indeed, they are handwritten) are imaginative lineal drawings, often complicated. It is notable that many of these "signatures" include the sign of the cross, which according to Christian tradition is opposed to demons and scare them. These signs appeared mostly during the Renaissance, in a time in which demonology was a subject of study for many theologians, priests, alchemists, kabbalists and other scientists and pseudo-scientists. One of the acts the Inquisition used to sentence Urbain Grandier to death had several of these signatures.

According to The Lesser Key of Solomon and the acts of some witch trials, there are demons that have more than one seal or signature.