A Rogue Captain is an attackable humanNPC that can be pickpocketed at 92 Thieving for 125 experience. They can be found in the Rogues' Castle in the Wilderness. Once a player has started to pickpocket from a Rogue Captain they will continue the pickpocket action without need to re-click until they are caught.
With a full thieving set-up (Trahaearn Exoskeleton, Abyssal Lurker familiar, Crystal Mask spell w/ Light Form prayer, and the Legendary Five-Finger Discount aura) and 99 Thieving, a player can average anywhere between 10-20 successful pickpockets before being caught. When caught pickpocketing at the Rogues' Castle, the player may not steal from rogues on that floor of the castle for 2 minutes, and must pickpocket on another floor until the rogues forget about the player's theft. Other than looting the Muddy chest, pickpocketing rogues is the only way to obtain additional Bloodweed seeds beyond the 5 daily seeds available in the Bandit Camp shop.