Bar-El and his wife Lilo are two of Krypton's first astronauts, and members of the House of El, Superman's family. Launched into orbit possibly centuries ago, they drifted until they arrived on Earth. Unfortunately for the couple, during their voyage they passed through the radiation cloud that changed hunks of Krypton into Green Kryptonite, causing the minerals in their body to change into deadly Kryptonite.
The two arrived on Earth while Superman was on Bizarro World, which had been sucked back into the Underverse from which it originated. The two set themselves up as the "replacement Supermen", and attempt to turn Earth into New Krypton. The two hold humans in disdain, referring to them as apes.
When Superman is able to return to Earth, he confronts the two in the Fortress of Solitude, which they have occupied in his absence. Bar-El assaults Superman, calling him out on his failure to enlarge the Bottled City of Kandor and keeping other survivors of Krypton in the Phantom Zone, despite them being insane criminals. Bar-El and Lilo beat Superman into space, and Bar-El punches him into the moon, causing the moon to crack.
Bar-El and Lilo later travel to Metropolis to confront Superman at the Daily Planet, in his guise as Clark Kent. While hovering in front of the building, their powers give out and they fall to the ground. Superman catches the two, and informs them about their weakening condition. Back at the Fortress of Solitude, Superman offers to do the one thing he can do: put them into stasis in the Phantom Zone, where their condition will not progress. Bar-El tells Superman that he is proud of him, as he has shown him kindness even in the face of anger. He requests Superman place his hand in Lilo's and the two are phased into the Phantom Zone.
Lilo has the same powers as Superman (like all Kryptonians under a yellow sun). Lilo has great physical strength (superhuman). Lilo also has speed, endurance, stamina, invulnerability much higher than normal humans. Lilo can fly and she can survive the vacuum of space.
Lilo has great physical force capable of launching Superman against the moon (the moon was damaged in the process).
Appearances in Other Media
Bar-El and Lilo both appear in the adaptation of All-Star Superman, which faithfully adapts their appearance therein. She is voiced by Finola Hughes.