The above quote from the new Monster Manual (Due out September 30th) described Thri-Kreen as they may appear in most standard D&D worlds. As we all know Dark Sun is far from standard. From the very inception of Dark Sun in the Original Dark Sun boxed set Thri-Kreen were heavily featured and available as a player character race.

With their four arms, carapace armor, leaping ability, and paralytic bite, the mantis warriors were a powerful race. In 2nd edition AD&D that power was limited by a short lifespan, trouble understanding and being understood by other denizens of Athas, and an inability to use many magic items and armor due to their odd insectoid body shape.

Origins

Thri-Kreen first appeared in the Dungeons & Dragons game with the Monster Cards accessories in 1982. From there they were published in the Monster Manual II for AD&D 1st edition in 1983. Following that they were included in the  Forgotten Realms setting  in 1989. After they appeared in Dark Sun, Thri-Kreen have been heavily tied to psionics and were included in several Psionic related books for 3rd edition D&D.

Appearance

Thri-Kreen are mantis men, with six limbs, four of which are arms, the remaining two are legs which were powerful and could propell them with huge leaps.. They are covered in chitinous plate armor and their mandibled mouths produced a paralytic poison that they could also use to fuse sand together to make crystaline weapons.

Thri-kreen appearance has mostly remained unchanged since their inception, with the exception of the abdomen. Up until 3rd edition Dungeons & Dragon Thri-kreen always had a large abdomen, giving them a very non-human appearance. With the 3rd edition Shining South book and for Dark Sun fans the  4th edition Dark Sun Campaign Setting their large abdomen was removed which resulted in a much more humanoid shape. One other notable change in their appearance is their second set of arms. In 2nd edition and prior, both their primary and secondary sets of arms were the same size, but in later (and the current incarnation) the secondary set of arms is smaller.

Near the beginning of the Dark Sun setting new types of thri-kreen were released, including the Tohr-kreen, and with the release of the Thri-Kreen of Athas in 1995 several sub-species of the insectoid men were produced.

Thri-Kreen in 5th Edition Dungeons & Dragons

In the new Monster Manual the Thri-Kreen gets one page, broken roughly into quarter it includes, a the picture, a  stat-block, a description of some of the races personality traits and habits, and variant rules which include weapons and psionics. This Thri-Kreen rules variant is great for Dark Sun fans and it shows how psionics can be used in a 5th edition game (by converting spells) even though specific rules for it are not yet out.

The Artist

The new 5th edition Dungeons & Dragons Thri-Kreen art was created as a water color painting by Russian- American artist Ilya Shkipin. You can find more of Ilya Shipkin's work at his website. Much of his online portfolio is contemporary illustration and fine art. For the new Monster Manual Ilya has painted the Thri-Kreen as an alien race with plate-like carapace and strangely angled insect limbs, fitting for the mantis men.  The pose has the thri-kreen holding a two bladed weapons that's not a gythka, more like a glaive,  as well as a chatkcha in a lower hand.

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