Can be found inside the corpses of (most) humans. You'll need to hold a knife or dagger.
Human hearts are used for the spells Doctor Kelleflump's Deadly Demon and Wungle's Great Sucking.
They can also be placed on the low altar of Sek in the Ankh-Morpork temple for a temporary +1 boost to strength. This stacks with other stat effects.
- Kess of Sek likes to remove and eat the hearts of her victims.
- Heartless lawyers literally have no hearts.