Xill
Xills are obscure monsters from Advanced Dungeons & Dragons that have been around since 1st edition. They are evil red skinned bug/reptile/diabolic creatures with four arms and paralyzing venom. They use the Ethereal Plane as a staging-ground whence they ambush and kidnap prey on the material plane, and also to spawn.
They first appeared in the Fiend Folio, perhaps inspired by the Assassin Bug. The Second Edition skipped 'em until Planescape; the 3rd edition promoted them to the first Monster Manual. They are also in 5th edition's Mordenkainen's Fiendish Folio, and in a few other miscellaneous books.
Xill reproduce by planting eggs in the bodies of kidnapped victims. The Fiend Folio stated that they are completely obsessed with reproducing to the exclusion of other interests - although being such coomers doesn't square well with their purported Lawful alignment. In 2e, Planescape retconned in "Monstrous Compendium Volume III" and "A Guide to the Ethereal Plane" that a "High Clan" exists who own cities in the Deep Ethereal, where they plant their eggs in slaves bred for that purpose - so they don't need to kidnap people. Such xill would indeed be Lawful so can be interacted with peacefully - though they are still Evil so, watch your ass.
3rd Edition states that groups of them are led by clerics, and the book "Defenders of the Faith" reveals they worship a god called Sixin. Beyond Countless Doorways posits the floating Wheels of Sostear, conjoined with Avidarel, on which the xill have built "hive-cities".
5e Mordenkainen's Fiendish Folio redesigns them to make them much more bug like and its left uncertain if they no longer reproduce using the people they kidnap. Their new lore states that they are the speculative creations of an evil wizard named Keraptis, a collector of artifacts, and the people that they kidnap are brainwashed into slaves for Keraptis.
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Pathfinder