The Sangheili Race
Sangheili are a raptor-like species, from the planet of Sanghelios of the Urs system. Standing between 2.2 and 2.6 meters long, their four-fingered hands give them the ability to create and manipulate their surroundings. This resulted in much weaponry, most notably their Energy shields and the Energy Sword.
The weapons they have created show their code of honour, mostly choosing close combat over long-ranged weaponry. Their code has limited them in more ways though: Their behaviour after being wounded, when their weapons are depleted and when their are (heavily) outnumbered. Sangheili usually prefer death over being wounded, which has resulted in unnecessary casualties. When their weapons are depleted or otherwise unusable, they will refuse to use non-Covenant weaponry; there have been cases of Sangheili being killed unarmed while surrounded by human weaponry.
Visited by Gods and Prophets
The Sangheili were visited by the Forerunner who planted a Halo Array close to their planet. After the detonation of the ring and their subsequent re-seeding, the Sangheili once again took over their planet and found Forerunner artefacts. They revered the objects as presents from their "gods" and considered tampering with them a heresy beyond any other.
When the San'Shyuum encountered the Sangheili, their use of Forerunner technology infuriated them and sparked the Sangheili-San'Shyuum war which lasted for 86 years. During the battles, the Sangheili superior fighting skill proved them powerful warriors, but they were eventually defeated by the San'Shyuums Forerunner dreadnought.
The battle ended with the San'Shyuum and the Sangheili forming the first Covenant Empire, with the Sangheili providing the military might while the San'Shyuum would serve as the religious leaders and scientists, studying Forerunner technology and seeking to discover how to use the Halo Array to initiate the Great Journey.
All Sangheili belong to their respective states, which is shown in their name; for instance Kaidon Thel 'Vadam is from the State of Vadam. Here, they have a very strong family connections. Family history and lineage are greatly valued, with each family having their own unique "Battle Poem" detailing the deeds and actions of its members during times of war. Their children are raised in "common rooms", where each child is equal and succeeds on their skill alone.
The Sangheili consider most other species to be inferior to them, both culturally and in fighting skill. Although Sangheili are naturally very intelligent, they mostly view might over science. Their rank structure is solely based on their lethality, after a certain amount of kills, they progress to the next rank.
The Sangheili display respect and admiration for honourable fighters, whether they are allies of the Sangheili or not. One such fighter is the infamous John-117, who they name "Demon" as a sign of respect. They also believe that blood can only be spilled in battle, and as such see medical attention (surgery) as shameful.