Tharrians
The Tharrians are a colonized race of humans from the 30th century who live in the hottest planet within the United Planets. Because of this all Tharrians can create and manipulate ice and cold. Polar Boy of the Legion of Super-Heroes Is a Tharrian.
Creation
The Tharrians first appearance was in DC Comics series the Legion of Super-Heroes "What Starfinger Touches...", part 1 of 2,
History
Original Continuity: New Earth

The Tharrians are originally colonizing humans who developed technology both biological and cryo-genetics to give the denizens of Tharr the ability to produce cold temperatures around their environment. The reason being because the although the planets core was extremally cold its surface was blistering hot and unlivable for organic life.
At one time the Tharrians were under subversive control of their government by the villain known as Starfinger and his gang. Then leader and native Tharrian Polar Boy would summon the Legion and help put an end to his plans.
Powers and Abilities
Tharrians have the innate natural ability to project and control extreme levels of cold temperatures. Some are extremely skilled with the ability and have shown to do a variety of controlled use of this ability.
Notable Tharrians
Polar Boy: Once the leader of the Legion of Substitute-Heroes who had traveled to earth as a youth to join the Legion of Super-Heroes only to be rejected. Somewhat of a local hero or a joke as a disappointing reject for years from the Legion.
Cryo-King: Villain from Tharnn who disdains the intrusion by the United Planets and the Science Police who has attacked UP Embassies on Tharnn.