There were always attempts to classify demons in several categories. Christian demonology accepted that, providing several classifications of the demons.
The first classification was the same that Judaism and other religions had, involving the demons' sexual behaviour (later this simple classification became complex):
But this classification soon became insufficient, and other demonologists suggested different patterns to classify demons. In this way there were classifications based on their nature, the sin with which they tempt humans, the month in which their power was stronger, the saints that were their adversaries, etc. Here follow some examples, listed in chronological order:
- Psellus' classification of demons (11th century)
- Spina's classification of demons (1467)
- Classification of demons by month (16th century)
- Binsfeld's classification of demons (1589)
- Guazzo's classification of demons (1608)
- Michaelis' classification of demons (1613)
- Barrett's classification of demons (1801)
There were other classifications, by office, like those written in several grimoires; these are some examples:
- Le Dragon Rouge (1522)
- Pseudomonarchia Daemonum (1583)
- The Lesser Key of Solomon (17th century)
See also Hierarchy of the demons.