The Spider Boss was a scrapped boss in Avant Gardens. To reach the Spider Boss, one would have to travel into the Spider Cave and use a Maelstrom Gas Mask (Which could be obtained in Alpha, but did not work). It is unknown what the player would have done next, or if it would have been like an instance like the Forbidden Valley Dragon Battle. In 2011, the Spider Boss was replaced by the Spider Queen. The Spider Queen was an easier, smaller version of Spider Boss. She was added when Free to Play came out and was the second battle instance players could enter (Which includes Avant Gardens Survival). Since the closing of LEGO Universe was announced, Spider Boss has been scrapped.
The lower parts of the Spider cave have been seen in a few trailers, showing web covered caves with Sentinel Guard NPCs and the Spider Boss himself. Through the pictures, it mentions that you must build the broken beacon that was destroyed in an ambush from Spider Boss himself. This may be a larger instance, where you must do a few quests and then find the Beacon and destroy the Spider Boss.
- In 2011, Spider Boss was replaced by the Spider Queen.