A mysterious character from the Teen Titans animated show, Red X was originally an alternate identity for Robin, but someone later stole the name & costume. Red X's motives are usually selfish & unknown. He made a comic book appearance in the show's comic spin-off, Teen Titans Go! Red X uses a variety of skill and gadgets to defeat anyone who stands in his way.
What does he stand for?
Red X was originally a cover identity Robin had conceived as an attempt to get closer to Slade. Mystified by the enigma the shady villain presented, Robin approached Professor Chang for the necessary items - particularly Xenothium for a power source - to create the Red X suit, and, posing as a superpowered master thief, Robin stole several computer chips Slade was after and offered them with a proposition to enter a partnership.
The New Red X
Some time later, however, the suit came into the possession of an unknown culprit who intended to use it for his own financial gain. Because the Xenothium supply in the suit's power belt was nearly exhausted, Red X stole a scanner which could locate the substance. Not knowing where to look for him, Robin coerced Professor Chang into revealing the most likely location where Red X could get his hands on more Xenothium: a highly secured tech company at the city's south end. Red X managed to penetrate the facility, with the Teen Titans in pursuit—but Professor Chang's henchmen were following them; Chang intended to swipe the Xenothium for his own to power a gigantic disintegrator cannon of his own construction. In order to ensure no interference from Robin, he captured the other Titans and held them hostage.
Who I think Red-X really is?
Jason Todd was a former Robin. In the Batman comics, Jason Todd was killed by The Joker but was later resurrected and became Red Hood. He is mentioned in the episode "X" where Beast Boy discusses who Red X really is. He had a drawing of people that could be Red X and Jason Todd is seen in the drawing as a theory.
The Teen Titans just caught Red X! As the team is about to unmask the villain, Beast Boy predicts he is Jason Todd, Batman's second Robin.
The Titans rip off Red X's mask, and, as predicted, he is Jason Todd! However, after closer analysis, Beast Boy tugs at Todd's face again to rip off another mask.
Under that mask is Titans East member Speedy! Starfire says that Speedy can't be Red X because he's standing on the other side of the room. Robin throws Rex X's mask in frustration and accidentally bonks Speedy on the head.
Robin rips off Red X's mask again to expose the Source. The block of tofu is quickly dismissed as Beast Boy eats his old foe.
Suddenly, another heads pops out of the Red X costume. It's Alfred Pennyworth! Alfred asks Robin to entie him, but, before he can finish his sentence, Robin pulls off another mask.
Under that mask, it's Batman! Batman begins to speak, but Starfire rips off the mask again.
The next person under the mask is Silky. Starfire chides her pet and pulls him out of the costume.
Another head pops out. It reveals itself as Larry the Titan. Robin quickly shuts up his fan by ripping off the mask again.
Finally, Red X reveals himself as Slade. Slade greets Robin, and the mask drops for a final time to expose a ticking bomb. The bomb explodes, and the Titans are flung to the ground.
While they are on the ground, the real Red X jumps on top of them and invites them to keep guessing before making his escape. Beast Boy shouts after him that he still thinks the villain is Jason Todd. Red X responded by throwing a sticky X at Beast Boy's mouth.
"Not everybody likes to play the big villain, kid. I'm a thief. I'm not threatening your precious city, just looking out for number one."
Robin confronted Red X about his self-serving attitudes, while Red X kept taunting Robin about the one mistake which helped create.
Red X's personality is the one major difference between him and Robin. While Robin was Red X, he was even more serious than normal and kept his goal of capturing Slade as his top priority. The new X, however, is a thief who is "just looking out for number one", stealing purely for the monetary gain. This Red X is revealed to be far less serious, finding his battle with the Titans amusing and being more concerned with messing with them than getting what he'd come to steal. Red X seems to have an attraction to Starfire, as he had tried flirting with her in the episode X. Although she rejects him, this factor proves that Red X and Robin both share similar tastes when it comes to girls.