Rath is the Codon Stream's DNA sample of an Appoplexian from the planet Appoplexia.
Rath is about 9-feet tall and resembles an orange and white bipedal tiger with one claw coming out of each hand.
Rath has super strength and agility, enabling him to jump great distances and lift objects many times his weight. As shown by how he was able to easily dismember the Forever Knights' paramilitary tank via brute force and toss the still extremely large pieces around (with one hand and later with two for the tank's body) with little to no effort in Duped. He also possesses a large, retractable black claw on each wrist. This claw can be used to stab and slice opponents or to create a shock wave when stabbed into the ground. Rath is also extremely durable, able to take a point blank laser blast with no damage, and survive a free fall from several stories. He is also one of Ben's most skilled hand-to-hand fighters, although not being one of the smartest.
Rath's brain made for aggression fighting as Rath's only known weakness is his lack of intelligence and highly aggressive temper. This causes Rath to become easily distracted and difficult to stop Ben transforms into him.. His apparent lack of intelligence also may convince him to needlessly argue with inanimate objects (shown when he screams at the Ultimatrix in Hero Time and in Prisoner Number 775 is Missing, when he screams at a Plumber's Ship, gravity and the hole he made when he fell.
- According to Eugene, Rath is probably his favorite alien, but he loves them all.
- It appears Appolexians are feared for their immense ferocity. The Vreedle Brothers tried to rally everyone in a seedy pit stop to fight Rath, just to run away seconds later. Rath was also able to terrify Jarrett, King of the Pantophage into a peace treaty, and the Forever Knights into running for their lives.
- Rath is Ben's only alien form so far that is willing to perform violent actions. All other forms usually retain Ben's desire to take down the enemy without killing them, but Rath does not shy away from the more extreme methods and suggestions to do so.
- Rath's claws resemble Toxicroak's claws from the Pokemon series.
- Rath os one of Ben's alien that does not need a spacesuit to survive in the vacuum of space.
- Rath is the second alien shown answering Ben's cell-phone (although it is almost as small as Nanomech to him because of his size), with the first one being Echo Echo.
- Rath is also the second alien Ben uses to jump down another alien's throat, the first also being Echo Echo.
- It is a running gag in the series for someone to correct Rath's messed-up metaphors.
- When Rath says "Let me tell you something..." he always says the person's full name.
- Out of all of Ben's aliens, Gwen and Kevin admit that they find Rath the most entertaining.
- Rath is the third alien to be unlocked by another alien, the first being Upchuck by Xylene in The Visitor and the second being Way Big by Azmuth in Ben 10: Secret of the Omnitrix, but this is the first one that is accidential.
- Rath doesn't seem to act like a tiger, even though he actually looks like a tiger, which are supposed to be cunning, strong, swift and very patient.
- In Ben 10-Generator Rex: Heroes United, Rath's fur is more visible and stands up along his entire body, but during the flashback scene in which Ben and Rex explained how they came to be, his fur wasn't visible and very much resembled his appearance as drawn in the normal style in UA and AF.