Easta Buni (pronounced the same as 'Easter Bunny') is an Ice Troll who featured in the 2010 Easter event. He was seen conversing with the Easter Bunny during the event, ordering something for Easter. He is so named because he was born around Easter-time, and apparently tried to eat the Easter Bunny. By Troll tradition, he was therefore named Easta Buni as Trolls are named after the first thing they (try to) eat. At the time of his release, he was one of the few trolls to appear in free players' worlds.
At the time of his release, Easta Buni, along with Undead trolls, were the only trolls in RuneScape with an updated appearance.
In the Knowledge Base article for the Easter event, a picture shows Easta Buni looking significantly different from in game. The in-game model resembled a mountain troll while the Knowledge Base model resembled an ice troll.
Easta Buni is the first NPC to have a voice. A player commented on this subject and Mod Fnord replied that it was indeed an NPC voice and that they are hoping to have more. Voices have since been added to the tutorial NPCs, some boss monsters in Dungeoneering, Nex and Bard Roberts, among other things.