Imps - Spirits of weak ability, often rude to compensate. They are only effective in extreme numbers or as messengers (20 magic, 30 intelligence needed for summoning)
Foliots - Spirits of more capable strength. They are weaker than djinn, but useful for everyday tasks too difficult or sensitive for imps. (40 magic, 50 intelligence needed for summoning)
Djinn - powerful spirits able to sustain high-powered magical attacks for a short period. (70 magic, 100 intelligence needed for summoning)
Afrits - Spirits of great ability. Due to being spirits of fire, they are near-powerless in water. Afrits are usually seen doing guard duty for prominent figures. (200 magic, 250 intelligence needed for summoning)
Marids - The most powerful of the regularly summoned entities. Marids are so powerful that they leave behind a trail of magic that can be traced, similar to the trail of slime left behind by a snail, but it is considered unwise to use this analogy to a Marid's face for obvious reasons. Because of their immense power all but the weakest Marids require two Magicians to summon. (350 magic, 400 intelligence needed for summoning)

Lesser Spirits
· Will-o'-the-wisps- Glowing spirits once used by magicians to lure travellers into bogs. Now they are reduced to hovering over manholes and the like.
· Mites
· Homunculi - Tiny Mannequins produced by magic. Some have prophetic powers but will always try to harm the magician
· Sprites
· Moulers - Small spirits, their stench causes unconsciousness
· Natterjack Implings -Basic spirit, one of the first a magician will learn to summon
· Search Sphere - Used for surveillance
· Scarlet Vexations - Carry disease

Imps
· Messenger Imps
· Shadow Stalkers
· Stygian Implets
· Goblin Imps
· Lamias - When summoned they must be played music to soothe them.

Djinn Sub-classes
· Cockatrices- Spirit with a deadly gaze, like the original Basilisk, so that one must wear mirrored glasses and place mirrors around the pentacle, with its instructions in a bowl, to safely control it.
· Demi-Afrits: Supposedly potent spirits that are close to, but not at, an Afrit's level.
· Ghuls: fond of human flesh, less powerful than most djinn.
· Horlas: powerful djinn that cause illness and despair in humans and sap other spirits' essence. Horlas appear as thin, smokey apparations with a human shape with glowing eyes.
· Krels: tall, thin, reddish djinn, usually used as sentries.
· Tracker Djinn
· Succubi: seductive female djinn, often unstable, and prone to recklessness and self destruction unless placated, "oddly" popular with male Magicians.
· Triloids: three-legged yellow sentry djinn, usually used as sentries. They are described as having three muscular legs which rotate on a hub of gristle. Above the hub of gristle is a blobby mass which sports two mouths and numerous eyes.
· Utukku: particularly unintelligent djinn that generally take the form of animal-headed warriors, and used as sentries at the Tower Of London (Bartimaeus's 5 steps to slaying an Utukku: 1. Pick up a rock 2. Throw it behind the desired Utukku so it makes a distracting sound 3. Watch the Utukku swivel around, eyes popping 4. Run it through the back with gusto 5. Gloat to taste).