The Tharils are leonine mesomorphs with yellow eyes, a shaggy brown-and-white mane hiding leonine ears, and furry hands and feet. Tharils are time sensitives, able to bring themselves into and out of phase with the timeline and thus travel the Time Winds unharmed. When out of phase, they can still manipulate objects in the normal timeline. They seem to have strong mental powers (it is suggested that they can blow up warp drives with the power of thought alone, and they can make people forget that they have seen them), and they can teleport themselves and others (possibly only if the other person is also a time-sensitive) simply by touching palms.
In times past, they used these powers to become the rulers of a vast empire that stretched throughout E-Space. At the height of their empire, they were able to bring foods from all over E-Space to their lavish banquets. The Tharils travelled through E-Space by means of their Gateway - a vast, bluish-white void in which an arched building containing a set of mirrors was situated. Beyond the mirrors was a reflection of the world on the other side, and the secret to crossing through them was a closely guarded one. Crossing the mirrors would heal injuries, whether inflicted by Time Winds or other means, and living tissue would remain healed on the other side of the mirrors. The area behind the mirrors, represented at least in part by a black-and-white garden, crossed the striations of the timelines. Only the Tharils were able to enter E-Space through them.
However, the Tharils abused their powers, and increased the strength of their empire by enslaving humanoids, possibly abducted from N-Space. With slave labor, they grew powerful, and created their empire by draining the life of the ordinary world. At first, the slaves could not approach the Gateway, but eventually they learned its secret, and they built Gundan robots to wage war on the Tharils. The Gundans, able to survive the Time Winds, were sent where no slaves could go, and defeated the Tharils, who were forced to flee through the Gateway for safety.
The Tharils' crimes then returned to haunt them, for raiders from E-Space soon learned that their time-sensitive nature made them valuable navigators. The Tharils were captured en masse and enslaved on many planets throughout E-Space. Connected to a navigation unit on the bridge, the Tharils were forced to visualize a destination, which was then displayed on a monitor over the Tharil's head. Once the image was firmly fixed in the Tharil's mind, it could jump the timelines and navigate the ship to that destination. If the Tharil had difficulty navigating, connection to a high-tension cable helped to stimulate its mind.
Due to their ability to teleport and travel on the Time Winds, the Tharils had to be contained using the only material that could restrain them - dwarf star alloy, made by compacting dwarf star molecules under enormous gravitational force. Entire ship hulls were made of dwarf star alloy, and the Tharils were also restrained with linked manacles which may also have been made of the same material.
They were sometimes transported from world to world in slave-trader ships, in which many Tharils were kept in storage, lying on bunks around the room, hooked up to respiration units and phasing slightly in and out of the timeline. They were revived from this state using equipment that apparently delivered an electrical jolt, but if the proper equipment was not used, this revivification process was likely to result in severe burns or even death.
One slave trader ship became stuck in the void of the Tharils' Gateway, and attempted to escape by creating a backblast to destroy the mirror. Instead, the mirror bounced the energy back at the ship and destroyed it. The Tharils were able to revive each other from the traders' storage, and escaped the destroyed ship to return through the mirrors. Romana and K-9 stayed with the Tharils, to help them rescue their people from slavery throughout E-Space.
