"Tero are more friendly and help keep the Dero in line , who are of reptilian nature, demented from having excessive power."
https://burlingtonnews.net/derros.html
"the DERO (or DEtrimental RObots), of a very negative-evil nature, and their nemesis, the peaceful TERO."
https://thinkaboutit.site/underground/a-guide-to-the-inner-earth-s/
"Standing between the viciousness of the degenerate dero and the surface civilization are the “tero” (“T” was the Atlans’ symbol of deity in their religion; therefore the “t” in tero represents good).
The tero have perfected methods of staving off most of the degenerative effects of their subterranean way of life by the use of certain machines, chemicals, and beneficial rays. Shaver’s “warning” to future humankind is that the dero are becoming more numerous and have scattered the benign tero with constant attacks."
https://occult-world.com/hollow-earth/
"One of the letters to Amazing Stories was from a woman who claimed to have gone into a deep subbasement of a Paris, France building via a secret elevator. After months of rape and other torture, the woman was freed by a benevolent Tero."
https://anomalien.com/deros-advanced-creatures-from-beneath-the-hollow-earth/
"These tero are locked in ceaseless combat with the dero, and some befriended Shaver: "Right under my feet men die on racks because the dero...have caught them trying to help protect Shaver."
The dero and tero populations of the caverns are dwarfed by a mass of human slaves as well as tribes of depraved freebooters who have drifted down from the surface world during various eras."
http://www.shavertron.com/feardownbelow.html
"the angelic Teros ("white hats" who sometimes intervened positively in human affairs) and the demonic Deros ("black hats," whose entire existence revolved around kidnapping, torturing and eating human beings).
https://www.salon.com/2020/08/23/the-deep-twisted-roots-of-qanon-from-1940s-sci-fi-to-19th-century-anti-masonic-agitprop/