Lionel Luthor is the name of Lex Luthor's father in the Smallville television series. Lex's father also made several appearances or mentions in the original Superman comics upon which the show is based, though his name there was never given as being "Lionel."

The Comics

In the Silver Age era Superman comics, Lex's father was a fairly nondescript individual who moved his family to Smallville, where his son Lex became friends with Superboy. However, after Lex's turn to a life of crime, Lex's father disowned Lex, moved with the rest of his family (which included his wife and Lex's young sister Lena) out of Smallville and, out of shame, changed their last names to "Thorul," an anagram for "Luthor."

Following John Byrne's 1986 revamp of Superman's origins, Lex's parents' backstory was altered so that Lex's father and mother were killed in an automobile accident perpetrated by their son. Lex had taken a large life insurance premium out on the couple, which Lex used to start his conglomerate LexCorp.

With the 2004 comic series Birthright, Lex's family history has been altered yet again, incorporating elements similar to the Smallville television show.

Smallville

In the Smallville TV series, in which he is played by John Glover, Lionel Luthor is very different than his comic book counterparts, who were fairly quiet and low-key individuals. Lionel has some of the comics' Lex's characteristics and he was the one to have his parents (one of them named "Lochlyn Luthor") killed with the help of criminal Morgan Edge.

Lionel Luthor is a sociopath, as lying and deceit are his most powerful weapons. He also uses his abundance of wealth and his twisted mind to devise numerous plans to get what he wants, because what Lionel Luthor wants, Lionel Luthor gets.

This proves to be true most of the time, except for when it comes to Clark Kent and the mystery of the Kawatchi caves. Luthor does all he can to figure out who Clark Kent really is, and more importantly, where he came from. He, like most others in Smallville, haven't any luck deciphering Kent or the caves.

Clark Kent and the caves were Lionel's primary missions, along with other usually business-related schemes. Unfortunately, Lex is also a victim of Lionel, as Lionel frequently puts Lex in harm's way under the motive to "make Lex stronger".

Lex has survived many attempts on his life and his buisness, no thanks to his father. All Lex really ever wants from Lionel are the things that are foreign to Lionel: kindness, respect, and love.

Recently in "Smallville", Lionel had a transformation into a good man...or so it appears. Lex doesn't believe the change is real, but Lionel tries to prove it to him with wise advice and genuine concern. He has given up his more recent mission to find stones that will give him copious knowledge, a mission that now Lex is bent upon.

As much as Lex tries to be his own person, there are signs that he will become what he has always fought against: his father. Only time will tell if Lionel is truly changed into an honest citizen, and if it is too late for Lex to make the same metamorphisis.