Helium is one of the major kingdoms in Barsoom. It is ruled by the Jeddak Tardos Mors and is the residence of warlord John Carter and his wife Dejah Thoris. Helium is noted, among other things, for the excellence of its navy (the fliers of Helium are among the fastest on Barsoom).
The two primary cities of Helium are greater & lesser Helium, located 75 miles apart from each other. Both cities have a mile-high tower rising from the center of them. These two cities function as the capital of the kingdom.
The greater city is distinguished by its scarlet tower, this is the throne of the Heliumite empire. Tardos Mors, the Jeddak, rules this city and the entire empire.
The main entrance to this city is The Gate of Jeddaks which opens onto the moss cushioned Avenue of the Ancestors, which stretches for five miles into the heart of the city in a huge plaza in front of The Temple of Reward.
The Temple of Reward is of particular note because it is here that heroes are honored, savants rewarded, and traitors punished. These individuals are led up the wide Aisle of Hope to the Pedestal of Truth where they stand before the Throne of Righteousness and are judged
The lesser city is distinguished by its yellow tower, it is ruled by its Jed Mors Kajak son of Tardos Mors.
- Hastor is located southeast of Helium, it is notable for its shipyards.
- Zodanga, itself a major kingdom, is located a thousand miles northeast of Helium. After the events of A Princess of Mars it is effectively a vassal state of Helium.
- Zor, A small red martian city that was conquered by Helium.
- John Carter - the Warlord of Mars. Formerly a captain of the Confederacy and a chieftan of Thark.
- Dejah Thoris - the wife of John Carter, and Crown Princess of Helium. Daughter of Mors Kajak and granddaughter of Tardos Mors.
- Carthoris - son of John Carter and Dejah Thoris, and a prince of Helium. Married to Thuvia, Princess of Ptarth.
- Tara - daughter of John Carter and Dejah Thoris and a princess of Helium. Married to Gahan, Prince of Gathol.
- Mors Kajak - father of Dejah Thoris, and a Jed of Lesser Helium
- Tardos Mors - Jeddak of Helium; grandfather of Dejah Thoris
- Uthia - Tara's beloved and loyal slave
- Kantos Kan - Jedwar of the Heliumetic navy
- Djor Kantos - son of Kantos Kan and padwar of the 5th Utan
- Jat Or - padwar and lieutenant of Dejah Thoris' personal guard
- Hor Vastus - padwar of Heliumetic navy
- Val Dor - a dwar renowned for his fighting prowess. Captured and enslaved in Manator, but later freed by Gahan.
- Zat Arras - man appointed Jed of Zodanga after it was absorbed by Helium.
- Gathol, is a small but wealthy allied nation.
- First Born, after John Carter overthrew Issus the first born of the Omean Sea became allies of Helium
the below information is not from the works of Edgar Rice Burroughs and therefore isn't considered canon
Helium is one of the main red martian kingdoms of Barsoom. The inhabitants of Helium are a regal, intellectual, and caring people. it is a civilization of sophistication, technology, and intellectual pursuits. For this reason it is reffered to as "the Jewel of Barsoom." The ruler of Helium is Jeddak Tardos Mors, but it has a representative government with a senate-like body.
Greater and Lesser Helium roughly 437 years before John Carters arrival on Barsoom were rival city-states in constant war. The war waged for centuries, it nearly culminated in victor as the forces of Lesser Helium, under the Jed Tardos Mors, managed to push their hereditary foes back to the crimson spire of Greater Helium.
At the time both cities were vassals of the nation of Yorn. The Jeddak Senneth Dor seemingly intervened and ended the conflict because he had chosen a wife for his son Dor Valian, the daughter of the Jed of Lesser Helium Dejah Thoris. The truth of the matter was that this was a ruse so that he could uncover the Colossus that was hidden beneath the city of Lesser Helium.
As Senneth Dor took control of the two cities he had the Jeds Tardos Mors of Lesser Helium, and Khanid Thal of Greater Helium imprisoned. The two were subsequently freed by Dejah Thoris, and ultimately they joined forces against Senneth Dor who had taken control of the Colossus.