Thieving God Idol ("Idol of Thieving God"), is an ancient magical idol that resembled a six arm beast that housed a demon like monster. It appeared in the Mirage Comics Tales of the Teenage Mutant Ninja Turtles and the 2003 TV series in the episode All Hallows Thieves.
The approximately 20 to 30 cm wide idol originated in India and represents a grotesque-looking, six-armed humanoid Kleptonis the God of thieves. This artifact has magical powers that it can reveal to a person only, if they prove to be a true thief in their heart and actions.
Among the known forces of the statue which can be released through appropriate knowledge of magic, include the summoning of countless winged gremlins or small demons, which are subject to the will of the summoner and can be sent out by him to collect all the available riches. In times of great distress, a knowledgeable user can even bring the statue to life and incite it against his enemies.
Some TMNT stuff was always meant for grownups.
Where the statuette of the Thieving God exactly originated from and how did it land in April O'Neil's antique shop, is unknown. However, it's whereabouts was identified by the King of Thieves who would be crowned the greatest thief in the world, in a (probably mythical) manner and stolen on his behalf by a few hired street thugs. The King, tried to harness the power of the statue to loot New York City down to the last speck of dust, but the Ninja Turtles, who got one of the thefts to tell them where they took the statue, did track down the King and his servant Hadji and did their best, to to spoil the soup in his plan. Then the King summoned the god for help, whereupon the statuette came to life and sought to destroy the Turtles. However, Donatello developed a plan to knock the statue off a apartment roof; as a result of this plan the statue crashed through the street down onto a main power line, which destroyed the demons and thus smashed the plan of the King. Then the statue was recovered by Donatello and placed in their hideout.
The King of Thieves later made trouble for the Turtles again when he and Hadji found a demonic artifact, the Hassock of the Nameless Chosen, which he wanted to use to bring the world under his control. The King made a mistake when reciting the spell, which would have given him control of the artifact, and was thrown by its power into an alternative future in which the world had been overrun by monsters (werewolves, vampires, etc.). To be able to return, the King had to bring the footstool a great sacrifice, but all attempts - including the sacrifice of the turtles - proved to be in vain.
Finally, the King attempted to use the idol as a sacrifice, and sent the animated skeleton of Raphael to get it from the past. But this accidentally sent the surviving Raphael into the future, where he met Hadji, whom the King had taken advantage of for his magical experiments, and Michelangelo (the only one of the turtles, who was still alive, but had now become a werewolf) and destroyed the focus that kept him trapped in this world - his own skeleton -. and thus trapped the King of Thieves forever in this hostile time
In the 2003 animated series the god whom represented the idol got the name Kleptonis (from the ancient Greek κλέπτειν ( kléptein ) = "steal"). Otherwise, it's story is that of its Mirage comic book template.
The idol at first it was on sale at April O'Neil's antique store Second Time Around. On Halloween a man who called himself the King of Thieves sought to posses the idol in order to become the greatest thief. At first the man asked April if she could hold on to it for him. Later at night a group of thieves attempted to steal it. During the theft the Ninja Turtles fought against them only to learn that thieves were hired to steal the idol. After obtaining the idol the King of thieves attempted to bring it to life using an ancient incantation. This incantation causes the six-armed Thieving God Idol to grow into a giant, living stone beast! The Turtles fight the monster allowing the King and Hadji to escape yet again. The two thieves make it to the streets, where the gremlins begin to pile loot up at their feet. Meanwhile, the Turtles are cornered by the seemingly invincible monster, so they head to the rooftops to have a better tactical advantage. As Mikey is about to be squashed, Don tosses his bo into the feet of the idol and trips the beast, sending it sprawling over the edge of the building. It falls through the pavement below and onto a subway platform. The Turtles follow and jump down into the tunnel to continue the fight. The monster emerges from a pile of rubble, one of its arms is now broken off. Leo takes one last swing at the beast and severs its left limbs - leaving it staggering. Raphael grabs the arm that fell off in the fall and attacks - knocking off the idols head with its own limb! The body staggers for a moment, and then falls off the platform right into the path of a moving train! The Thieving God Idol idol is smashed into pieces - which soon glow red and disappear.