Lex Luthor's father was first introduced in Superman comics by Jerry Siegel in 1961 and has since appeared in other Superman-related media under different names.
He debuted in Superman's Girlfriend, Lois Lane #23 (February 1961) and was created by Jerry Siegel and Kurt Schaffenberger.
A parallel universe version of the character is later introduced in the show's final season, who serves as Clark and his allies' adversary and plays a pivotal role in bringing Lex back from his presumed death.
Lionel's development from a main antagonist to an ally was difficult for the writers, who felt the character's arc failed to achieve the status they wanted.
[1] In 1989, Lionel visits Smallville to buy the Ross Creamed Corn company immediately before a meteor shower occurs.
Twelve years later during season one, Lionel exiles his son Lex Luthor (Michael Rosenbaum) to Smallville to run LuthorCorp's local fertilizer plant as a test.
Lionel later confronts his son at the Luthor mansion when Lex tries to orchestrate an employee buyout to save the fertilizer plant.
When strong winds force debris to smash through the mansion, Lionel is pinned under a fallen support beam and Lex hesitates to save his father.
[5] Lionel is later aware of the Kawatche caves and tries to unlock the mysterious symbols there, to the dismay of Clark Kent (Tom Welling).
[7] When Chloe Sullivan (Allison Mack) discovers the truth,[8] that evidence is used to assist Lex have Lionel arrested for his parents' murder.
[14] Lionel is released from prison by Genevieve Teague (Jane Seymour), and begins searching for three stones of knowledge.
[15] Lionel recovers in season five when the Kryptonian artificial intelligence Jor-El takes over his body to speak with Clark.
[17] Season seven revealed that Lionel and three other wealthy families formed the secret society Veritas to protect an alien visitor known as the Traveler (Clark).
[18] Season ten reveals that Tess Mercer (Cassidy Freeman) is Lionel's illegitimate daughter fathered with Pamela Jenkins (Donna Bullock).
[20] Lionel posed as his own doppelgänger as he assumes control of LuthorCorp from Tess and attempts twice to groom "Alexander Luthor"/Conner Kent (Lucas Grabeel) to his side.
However, Lionel fails to bring the hybrid clone of Clark and Lex to his side and loses the company when Tess proves he's an imposter.
He founded the genetic research company PreClox as he embezzled a large amount of money from LuthorCorp to assist Lex's scientists.
[23] Lionel Luthor was created by Alfred Gough and Miles Millar specifically for "Smallville" to provide a parallel to the Kents as an "experiment in extreme parenting".
This helped Glover understand how someone powerful and full of life could commit suicide—which Lionel prepares to do when he learns his illness is terminal.
Executive producer Greg Beeman said the character development failed, and as a result Lionel returned to his normal self.
[30] Glover said he believes Lincoln Cole's (Ian Tracey) actions in "Mercy" made Lionel rethink everything his past behavior and his own character.
When Lionel is in Martha's company he tries to present himself as a man she could be with; he consciously attempts to change years of selfish behavior.
When Martha left the show, writer Todd Slavkin said they wanted to give the character "more of a send-off" than they achieved on screen.
The writers realized they could not kill off the character so they sent her to the U.S. Senate, creating a parallel to Clark where Martha fights injustice on the political stage.
[31] Glover describes his off-screen relationship with Annette O'Toole the reason Martha and Lionel have such good chemistry.
Glover said that when Martha and Lionel are talking to each other it feels as though he and O'Toole are sharing a conversation, and that trust is visualized on the camera.
[30] For his portrayal of Lionel Luthor on Smallville, John Glover was nominated for two Saturn Awards in the category of Best Supporting Actor in a Television Series.