The Other were a species of Humans, specially modified for war.
Biology
The Other were humanoid in basic appearance, but were heavily modified with reptilian and insectoid traits. They had sharp claws and teeth, eyes protected with a double layer of scales, natural armour around their torso and a long forked tongue. Their senses were silicon enhanced and the computer systems were hooked up to their hippocampus, allowing them to keep in constant contact with their ships. (VD: Aliens and Predators)
Technology
The Other who were trying to attack the Hope used a ship of similar size, along with a fleet of smaller ships for frontal assaults. The ship had an advanced computer system which could track the changes in the Hope. Individual Others had neutron-cutters and weapons capable of firing micro-thermonuclear blasts. (VD: Aliens and Predators)
History
The Other were originally Human, but over time they modified themselves until there was little humanity left. During the time period they were active, they were one of the most feared races of the Galaxy.
When the ship Hope was created, the Others began to chase it, trying to get the Human DNA stored on board. They chased them for eighty years, never gaining much headway. They were eventually able to kill three of the Guardians and storm the ship, but the boarding party was all killed. When Jamie McCrimmon accidentally set off the self-destruct system of Hope, the Guardians decided that there was nothing left to save and allowed the ship to explode, killing the Others. (VD: Aliens and Predators)