Jeff Palmer, aka The Invisible Man, is the very protective brother of Amy Palmer and served as the main antagonist in the First season of Smallville episode "Shimmer".
His parents worked on the staff at the Luthor Mansion. He found some strange green (meteor rock-mutated) roses on the grounds of the mansion. He studied them, extracted the oils, and created a cream that rendered him invisible.
Jeff's sister was obsessed with Lex Luthor, and jealous of his current house guest, Victoria Hardwick. During gym class, Troy Turner snatches Amy notebook from her to see if she is writing about him, but its all about Lex Luthor. Amy's brother Jeff arrives just then to rescue her.
In the locker room, Clark Kent feels a bit ill as an invisible assailant walks by and clobbers Troy with some small free weights. Clark and Pete arrive to help. The invisible assailant can be seen as he walks through the steam, but no one notices.
After an encounter with Victoria left Amy in tears, her mother counsels her that even though they live on the Luthor Estate, they are not a part of his world. Jeff assures their mother that they know their place.
Jeff used his invisibility to vandalize Victoria's room, making Lex think there was a "ghost" haunting his mansion, but when she still didn't leave, he tried to drown her in her bathtub. One day after Amy had another jealous attack he went for Lex, attacking him and shouting at him to choose Amy over Victoria. Clark came to Lex's side and Jeff had some knowledge of his abilities and smacked Clark in the face with a mace, which shatters upon impact.
After his battle with Clark Kent, he was taken away in an ambulance in need of some "serious therapy."