Vadam is a Sangheili family. They lived in the State of Vadam, a relatively young yet powerful state in Yermo, Sanghelios. Their kaidon during the Human-Covenant War was Thel 'Vadamee, who would soon be the Supreme Commander of the Fleet of Particular Justice, and later the Arbiter. To gain the honor of having the suffix -ee added to the end of Vadam, the Sangheili would have to have military service.
Vadam Keep stands on Kolaar Mountain, Sanghelios and was founded during the Sangheili's first exploratory age. Thirty miles away, there was a harbor which brought profits and wealth for the state of Vadam. The land also seemed well-developed; buildings stretched across the entire state from the valley under the keep to the fields where the serfs worked. The Vadam serfs also seemed strongly motivated and efficient, as their great ambitions were to rise, gain distinction and receive a position inside the keep.
A story told by the future Arbiter about Vadam said that at one point the house was captured by an opposing clan and the Sangheili of Vadam were forced to rot within their own fortress's dungeons. Their kaidon, Ther 'Vadam, soon escaped, however, due to the fact that he was skinny enough to slide through his cell's bars. He escaped to the desert and quickly grew in power, and recruited bandits and outlaws to form an army. Soon, Ther returned to what was rightfully his with his army, scaled the walls, and killed all his enemies before throwing their bodies in the river; legend has it that the river ran purple with Sangheili blood for days. After this was done, he killed those of Vadam who had been foolish enough not to commit honorable suicide within their dungeon cells.
This passage of Sangheili history demonstrates the harsh lifestyle and honor-based society of the Sangheili.
 Known members
- Thel 'Vadam - Kaidon
- Lak 'Vadamee - Elder
- Koida 'Vadam - Elder (deceased)
- Unnamed descendants
- Ther 'Vadam - Ancient kaidon