Lesser Demons

From Runescape - Wiki on Neoseeker

Lesser Demons are level 72 demons that are found in several places in Runescape. They are a popular F2P monster that is often killed in the volcano dungeon on Karamja. They also drop rune full helmets and other rune items, making them useful training for mid level players. One can be found in the Wizards Tower also, which is often maged due to it being caged. Items dropped by it however cannot be picked up unless you use the telekinetic grab spell.