Yellow Zelkova

Yellow Zelkova is a antagonist from Sonic X. Yellow Zelkova is a bulky Metarex commander with a deep green visor, bulky yellow armour and a long green cape with a matching orbs on his head. Zelkova considers himself the (physically) strongest Metarex commander, and brute force is his answer to everything. Zelkova's height seems to change throughout the anime. At one point, he is about that same size as other Metarex, and would be about twice Sonic's height. However, in his final fight against Knuckles, his foot is large enough to crush Knuckles and hide him from view.

Zelkova first engages Sonic and co. when Dark Oak dispatches him to the Intergalactic Cloister to get rid of Sonic and co. He puts up a good fight, however he proved too slow to defeat Sonic and Knuckles, the latter of whom he formed a rivalry with. However, he was the first Metarex to survive a direct hit from the Sonic Driver on the Blue Typhoon. He swore vengeance, vowing that the Metarex would destroy them. He later joined up with the other commanders to attack the Blue Typhoon, though he strongly disapproved of Doctor Eggman's joining forces with them.

He later attacked the Blue Typhoon again, equipped with a special shield pack that blocked all of his enemies' attacks. However, his shield proved ineffective against his rival Knuckles, who smashed Zelkova's knee, though it broke two of his fist spurs. Sonic and co. then used collected lightning to overload Zelkova's generator, destroying his outer shell and revealing Zelkova's true form: that of a massive male specimen of Cosmo's species. Zelkova was then knocked into a nearby lava pit by Knuckles' punch. Knuckles jumped into the pit to try to save Zelkova, but Zelkova refused, slid into the lava, and died (ala Sonic OVA). However, the dub cuts the part just as Knuckles jumps in.

Yellow Zelkova is not the brightest in the bunch, considered an invalid by both Dark Oak and his comrades Black Narcissus and Pale Bay Leaf. His gullible nature can be seen when he shows his shield pack made by Eggman, as after he finishes bragging about it, he adds "And that's not all! As a bonus, I get this Eggman temporary tattoo!" (this line is only in the dub, not the original). Unlike most Metarex, he uses no weapons, relying on his fists and head to attack enemies, as well as anything that he can throw at his enemies. However, he has far more physical strength than the other Metarex commanders, and his body is extremely well armored (how strong his shell is is a bit inconsistent, in his debut his survives a hit from the Sonic Driver, but his final battle with Knuckles was able to destroy his outer shell). Zelkova was also shown among the leadership council that was present when Hertia declared that they would be abandoning their homeworld, and was alongside the revolutionary Lucas in refusing to depart after fighting so long, possibly implying he was of high rank on the planet.