Luthor ala Superboy
This is a still from "Superboy" (88-92) This is a pic of Scott Wells as Lex. Scott was replaced by Sherman Howard. (Like John Haymes Newton being replaced by Gerard Christopher.)
Primetime Luthor
This is John Shea. Who played Lex Luthor (Both with hair and bald.) opposite Teri Hatcher and Dean Cain on "Lois & Clark" Oddly enough he is just a little bit (a couple months) older than Sherman Howard. (Luthor #2 Superboy)
Lex Luthor ala Smallville
This is Michael Rosenbaum, Lex Luthor on Smallville. In this continuity Lex and Clark are friends at this stage and we eventually will see him turn to the dark side. Smallville can be seen on the WB Wednesday night 8pm eastern 7 central.