Athlon Theta is one of Kyle Hughes's three Athlons, along with Alpha and Beta. Theta is not a racing Athlon, but is still integral to the robot races; every pilot controls his racing robot from the back of a command vehicle. Therefore he embodies the role of a guardian and carries Kyle on his back for aerial surveillance in the races.
Theta is pretty shy and only speaks when he has something important to say. He has protective bubble abilities that he uses to keep Kyle safe during the races and in his day-to-day life, so this Athlon reflects and represents the responsible side of Kyle's personality. 
Voice Actor: Ha Ryong-i/하룡이 (Korean), Tyrell Crews (English), more...
Theta does not have any offensive moves, though he can help out if needed. Most of his skills support his fellow Athlons.
- Bubble Sphere
Theta's signature move. Theta wraps himself in a bubble coat, which deflects both physical and projectile attacks.
- Bubble Sonic
Theta releases a sonar wave to track down his allies.
- Bubble Man
Theta launches inflatable dolls that block attacks. And giggle when hit; that's very important.
- Athlon Theta/애슬론 세타 (2015)
- Accessories: Mind Core, Kyle figure, stickers
Theta has a somewhat more involved transformation than Alpha or Beta. Though his leg articulation is decent, his arms are pitiful, only spreading out one click, moving forward 90 degrees, and bending at the wrist. A slot on his chest stores the Mind Core, which is required to keep his head up. Amongst other places, Theta's head is significantly lacking in paint.
Every Theta is packaged with a Kyle figure, which can ride Theta's backpack. (albeit only upright)
This toy is a shelfwarmer, and as such his retail value remains the same on the secondary market, while new copies of his teammates have inflated prices.
- Minipop Theta/미니팝 세타 (2016)
Instead of the usual mini Tobots, Young Toys opted to release one-button transforming "Minipop" toys for Kyle's Athlon trio. Minipop Theta, as well as Alpha and Beta, transforms from a car to a robot at the press of a button, but lacks all articulation except a slight bend in the elbow. The backdrop in the box can be used as a display in bot mode or a ramp in car mode.
An orange Theta with metallic red stripes forms the arms of Champion.
A blue Theta with red stripes forms the left leg of Magma 6.