Collector was a hard difficulty stamp in Club Penguin. In order to obtain this stamp, the player had to buy every single item in Club Penguin: Game Day!. For a full list of the items required, see here. Note: the backgrounds and colors were not required for this stamp.
This stamp was a bait item if the player attempted to perm it.
This stamp became unavailable, due to Nintendo no longer supporting Nintendo Wi-Fi Connection for Nintendo DS and Nintendo Wii systems, thus preventing stamps from being transferred from the game to online.