Zombies could be encountered in Lumbridge Swamp during the 2005 Hallowe'en event. There were three types of zombie, which could be interacted with in three different ways. The first kind of zombie could be called-over, and would split into two Most of a Zombie, one comprised of the upper half of their body, and the other the lower half.
The second type of zombie could be insulted, causing its head to fall off, leaving behind a headless Most of a Zombie and a Zombie Head, which could then be caught to obtain the zombie head item.
The final variety of zombie could be scared, which would cause them to split into Half-Zombie and Other Half-Zombie and in turn spare the player, unlocking the Scared emote.