The Short Mischievous Scientist appears in Episode XLIX: The Four Seasons of Death.
The Short Mischievous Scientist is a small, bald, gremlin-like alien with greenish-blue skin and spindly limbs. His eyes are hidden behind black goggles with red lenses, which can move independently of each other. He has a wide mouth filled with sharp teeth and a frog-like tongue, which he uses to catch and eat a wasp during his hunt for potion ingredients.
Although he cannot speak, the Scientist appears to have a sadistic streak, giggling constantly and preparing potions with bizarre and deadly effects. It is unclear if he is truly villainous (and possibly working for Aku), or if he simply has a strange and dangerous sense of humor. Either way, he appears to be very hyperactive and high-strung, often sweating profusely as he goes about his work.
The Scientist is introduced gathering ingredients for a potion that will make the drinker "one with nature." The process involves collecting certain leaves and flowers from the fields outside his windmill laboratory and mixing them with various chemicals. After a lengthy process (not helped by having to wait for the blades of the windmill to pass by his door every time he enters or exits), the potion is complete.
With his new chemical ready, the Scientist pours the potion into a well, where it seamlessly mixes with the water. He then hides in a bush as Jack walks by, clearly eager to see his potion's effects on the thirsty samurai. Although Jack seems briefly suspicious when the scientist's sweat disturbs a leaf, he drinks the water nonetheless; moments later, he gags and collapses on the ground.
Believing his experiment to be successful, the Scientist bursts from cover and runs to the unmoving samurai's body. Suddenly, Jack turns his head and spits the water into the Scientist's mouth; he had suspected a trap and only pretended to swallow the water in order to lure the perpetrator out of hiding. In his surprise, the Scientist swallows the tainted water, dying when his body turns into leaves that blow away in the wind.
It is unknown how the past Aku's destruction affected his existence.
- The Scientist shares some design similarities with the Guardian; both have blue skin, red-lensed eye-wear, and a near-constant toothy smile.