The famous scientist father of the more famous Kryptonian scientist Jor-El II, and therefore the grandfather of his son Kal-El--the legendary hero better known as Superman. Jor-El I is also the father of Jor's twin brother, Nim-El and younger brother, Zor-El. He is also the grandfather of Supergirl (Kara Zor-El) and her cousin, Don-El (WK No. 1, Jul 1979: "The Jor-El Story"; and others).
When Jor-El II and Nim-El were still infants, Jor-El I succeeded in journeying to Earth and back in an experimental spacecraft of his own design (S No. 103/1, Feb 1956: "The Superman of Yesterday"), and although knowledge of the craft's construction had apparently been lost to Kryptonians by the time Jor-El II reached maturity (Act No. 158, Jul 1951: "The Kid from Krypton!"; and others), there can be little doubt that his father's achievement served to inspire his own explorations into the then-infant sciences of rocketry and space travel. (TGSB)
Shortly after the marriage of Jor-El II to Lara Lor-Van, the elder Jor-El summons his son to the ruins of Antarctic City. Jor-El I has recently made two important discoveries. Before he can tell his son what he has discovered, the rocket-sled in which the two scientists are traveling is overturned by an ice bird. Jor-El I is rendered comatose. During his coma, the younger Jor-El uncovers one of his father's discoveries from Jor-El I's notes. Krypton is going to explode!
Sometime later, Jor-El I awakens from his coma just long enough to tell his son of his other discovery. Jor-El I has found an ancient spaceship built by the alien Krull race. He hopes that Jor-El II will be able to reverse-engineer the technology found in this ship to build a fleet of craft capable of evacuating the people of Krypton. Jor-El I then expires from the injuries sustained in the ice bird attack.
Jor-El II swiftly begins working with Nim-El and others on ships to save his people in the capital city of Kandor. However, Kandor is soon shrunken and bottled by the Coluan android menace called Brainiac. Zor-El and Nim-El are both in Kandor when it is taken and thus survive its ultimate fate. Both eventually marry and become fathers. In the end, Jor-El II is only able to build a small rocket large enough to send his infant son Kal-El to Earth before the destruction of Krypton (WK No. 2, Aug 1979, "This Planet Is Doomed!"; WK No. 3, Sep 1979: "The Last Days of Krypton"; and others).