According to Church of Scientology doctrine, Helatrobus was an "interplanetary nation", now extinct, which existed trillions of years ago.
In his State of OT lecture, Scientology founder L. Ron Hubbard described them as:
"a little pipsqueak government, didn't amount to very much."
This same description also appears in the Dianetics and Scientology Technical Dictionary (first edition, pg. 196). The official insignia of Helatrobus was a gold cross, "like the American Red Cross or something of the sort."
In the HCO Bulletin of April 17, AD13 ("Aircraft Door Goals"), Hubbard states that the total life span of the Helatrobus government was between 52 trillion and 38 trillion years ago.
Despite Hubbard's description of them as small and insignificant, he attributed to the Helatrobans a set of "implants", including the Heaven Implants, given 43 trillion years before the present, (SHSBC tapes 294, 295 and 300 - #s 6305C21, 6305C23 and 6306C11) and the Gorilla Goals, created "between about 319 trillion years ago to about 256 trillion trillion years ago" (or 89 trillion trillion years ago, according to a different lecture). ("Routine 3N: Line Plots", HCOB 14 July 1963).
Hubbard also discoursed on another set of "Helatrobus Implants", located "382 trillion years ago to 52 trillion years ago". In a series of lectures, Hubbard gives further detail:
Planets were surrounded suddenly by radioactive cloud masses. And very often a long time before the planet came under attack from these implant people, waves of radioactive clouds, Magellanic clouds, black and gray, would sweep over and engulf the planet, and it would be living in an atmosphere of radioactivity, which was highly antipathetic to the living beings, bodies, plants, anything else that was on this planet. And so planetary systems would become engulfed in radioactive masses, gray and black. And the earmarks of such a planetary action was gray and black – gray towering masses of clouds. These Magellanic clouds would not otherwise have come anywhere near a planetary system.
("State of OT")
When a planet was engulfed, the Helatrobans attacked it with "little orange-colored bombs that would talk", and the clouds themselves would speak: "And here you'd have a gray cloud going by and it'd be saying, 'Hark! Hark! Hark!' you see? 'Watch out! Look out! Who's there? Who's that?'".