H’El

H'el is a fairly new character, having debuted in the pages of DC's New 52 relaunch. H'el is a clone created from the cells of countless Kryptonians, who believes - thanks to false memories - that he was once the prized student of Superman's father, Jor-El. H'el becomes the first Kryptonian test pilot in centures and, on his maiden voyage, is lost in uncharted space. H'el winds up on Earth, 27 years after Krypton's destruction. He then vows to go back in time and stop the destruction of his homeworld, even if it means destroying Earth in the process. Bringing him into the story could add a great deal of drama to the Supergirl series, as it would force Kara to choose between her homeworld and Earth - the planet she has just sworn to protect.