Season 9 Of Smallville

After Winslow Schott (who was arrested for Lex's murder) was arrested a year later for escaping and attempting to murder Oliver, Oliver briefly hallucinated Lex in his reflection. After seeing Clark's fate, Doctor Fate told Clark Kent that Lex Luthor would become Clark's ultimate opponent in the future, but assured him that he would one day finally triumph over Lex. Clark questioned this, believing Lex had been killed to which Doctor Fate did not respond.

In Clark's dream of the future, Lex had already publicly returned from his seeming death and was running against the current President in the 2013 Presidential election, to the disgust of Lois Lane.