My name is lex!
Michael Rosenbaum is no longer involved with the show during season 8, they use stock footage and stand-ins to imply Lex Luthors continual involvement in the story line. Rosenbaum has been quoted as saying his disapointed that they are using his image and implying to the fans that he is still there. There are rumors that he may return for the shows finale episodes (whenever that may occur)
Julian
John Glover did not leave Smallville of his own choice the writers of the Smallville series had made the decision to write him out by making it so that his own son; Lex Luthor would murder him however the writers later brought John Glover back in Season 10 as Lionel Luthor but as Lionel Luthor from another alternate reality in which the Luthors were the one who had found and adopted Clark Kent and therefore became Clark Luthor.
However old this question is, it is now Season 10, in 2010-2011. Chloe has never really been gone longer than two episodes, so yes she is still here in all 10 seasons. Tess is still there, too. Lex may be coming back! I mean he is the main villian! I think that since black kryptonite split the good and bad Lex, and the bad Lex disappeared, and Oliver killed Lex, I think that the good Lex was killed, but the bad Lex lives and will come back.
Green skull
Kitty Kawolski
He can shoot missiles, fly with his jet shoes, and use a flamethrower in his green and purple power suit. I have also seen him in other suits but I think the green one is his main suit.
My name is lex!
Lex Medlin's birth name is Lex Michael Medlin.
Yvonne Lex's birth name is Douliez, Yvonne.
Lex Lovett's birth name is Wayne Meyer.
Lex Henderson's birth name is Ibrahim Badmus.
Lex Shrapnel's birth name is Alexander Carey Shrapnel.
Lex Kreps's birth name is Alexis John Kreps.
Lex Lamprey's birth name is Alexander Jon Lamprey.
Yara Lex's birth name is Iracema Pedrina Barreto.