Experiment 221, also known as Sparky, is a character that appeared as a boss in the Lilo & Stitch-based world, Deep Space, in Kingdom Hearts Birth by Sleep and Kingdom Hearts Birth by Sleep Final Mix. He is one of Jumba's original 625 experiments. His "primary function" is to short out electrical devices.
Experiment 221 prefers to be left alone, using its powers and combining them with a hot and defensive temper when provoked. He longs to be free, and is otherwise "harmless", his only goal to carry out his primary function.
A short and squat yellow extraterrestrial, massive blue eyes shine on Experiment 221's narrow, football-shaped head. On either side of his head is a small ear. Long, forked antennae protrude from either side of the eyes, large and flat teeth sticking out in its blue mouth beneath its domed, yellow nose.
This Experiment's belly is white, a short tail sticking out behind it. Experiment 221 has the ability to sprout an extra pair of arms, while this has yet to be seen in Kingdom Hearts Birth by Sleep, its short body extending into a long streak of a tail as it moves through the air at high speeds, its body shining with electricity.
When Terra and Jumba reached the room that Experiment 626 was being contained in, Jumba tells him that he had created him for the purpose of evil, and that he was designed to wreak havoc and destroy everything that he touches just as he releases Experiment 626. Experiment 626 then lunges at Terra and steals his Wayfinder. Terra cries out that a friend gave him that and begins to realize just how much he misses them. Experiment 626 drops the Wayfinder and leaves the room which makes Terra question Jumba if his experiment is really all that evil.
Angered by the question, Jumba assures him that he is and asks "Or do you need another demonstration of my evil geniusness?!" He then pulls out a small green ball and a test-tube filled with water and laughs hysterically as he places it in the water. Experiment 221 emerges and attacks Terra. When Terra defeats Experiment 221, it reverts back to its pod form. Jumba then reassures it that everything will be all right just as Experiment 626 reenters the room.
Experiment 221 is an agile fighter, using electrical attacks to deal massive damage. It can also manipulate objects, possessing the blasters hanging from the ceiling to fire a series of blasts at Terra.
Experiment 221 made his first appearance in Stitch! The Movie. In the film, he is the first of the original experiments to be activated from pod form. He is activated by Lilo and Stitch when they need to recharge Jumba's ship. However, he goes on a rampage throughout the town, shorting out any electrical appliances in sight. Soon, Lilo and Stitch manage to catch him, and convince him to be good. He is then left in the old Lighthouse, providing the electricity needed to turn on the light, and thus, fulfills his "primary function". Just like Stitch, Lilo gives Experiment 221 a name of his own, Sparky.
- As the events of Deep Space take place before the events of the movie and its sequels, this is before Experiment 221 is named Sparky, just as Stitch is still known as Experiment 626 at this time.
- Since Stitch! The Movie revealed that Stitch knew nothing of his cousins before finding the containment unit, it's unknown if he knows of Experiment 221's existence in Kingdom Hearts Birth by Sleep. While both appear in Kingdom Hearts Birth by Sleep, 626 flees the chamber in which he is held captive before Dr. Jumba activates 221 to battle Terra, implying that he doesn't know.
- For a while, Experiment 221 remained the only Disney character in Kingdom Hearts to have his debut in a direct-to-video feature rather than a theatrical movie, until the debut of the Beagle Boys in Kingdom Hearts 3D: Dream Drop Distance.