Catapults

John Howe - Trebuchets

Catapults were siege engines used for casting missiles.

During the siege of Minas Tirith the Morgul-host led by the Witch-king set up great catapults, which were used to throw into the first circle of Minas Tirith both flaming missiles to cause fires and severed heads of fallen Gondorians to cause dread and despair. Gondorians also had similar engines upon the walls of Minas Tirith, but they were smaller and couldn't reach catapults of the enemy. It is possible that these Gondorian catapults were later used to crush or set aflame siege towers used by the besiegers.

Portrayal in adaptations

2003: The Lord of the Rings: The Return of the King:

The Morgul-host uses catapults, operated by Orcs and Trolls. They launch both severed heads of Gondorian soldiers and flaming missiles (as in the book), but also stone missiles, able to damage the walls of Minas Tirith.

Gondorians use trebuchets, which launch pieces of broken walls instead of dedicated missiles. They are used successfully to destroy several siege towers of the enemy.