Dr. Frederick Walden is a recurring antagonist in Smallville, appearing in multiple episodes in Season Two. He is a world-renowned linguist hired by Lex Luthor to decipher a series of alien symbols within the Kawatche caves beneath Smallville. He was the main antagonist of the episode "Calling".
He was portrayed by Rob LaBelle who played Azazel in Supernatural.
Dr. Walden was a brilliant linguist and published a book entitled Deciphering the Mysteries of Hieroglyphics. which Clark Kent used to study the etchings in the Kawatche Caves. Lex Luthor discovered Clark's copy of the book and hired Dr. Walden to translate the strange markings. Lex Luthor discovered Clark's copy of the book and gives Clark unlimited access to the caves.
Lex approached Walden who offered to pay him handsomely for his assistance in deciphering an alien language (later revealed to be Kryptonian) inscribed within a series of caves beneath Smallville. At first, the doctor was uninterested and Walden claimed he cannot be swayed but changes his mind when Lex shows him photographs of the cave paintings. His curiosity piqued, Walden agreed to work for Luthor.
While Clark and Chloe were at the caves, Lex and Dr. Walden appeared and said nobody can have access to the caves, including Clark. The doctor reveals that his team found a nest of parasites behind one of the glyphs in the cave wall. Lex orders any live specimens to be sent to Cadmus Labs in Metropolis.
Afterwards Lex gets off the phone with Cadmus Labs and found out that the parasite could be alien in origin. He tells Dr. Walden that Clark gets unfettered access to the cave because he is sure Clark knows more about the cave than he's letting on. Walden accepted though he was clearly aggravated by Lex's decision to allow Clark Kent unlimited access to the caves.
Dr. Walden arrives at the Luthor Mansion, and Lex questions his decisions regarding the caves, thinking Dr. Walden is cutting him out of the process. He says the State Preservation Society is objecting to Dr. Walden's intention to remove a section of the cave wall and is on the verge of revoking LexCorp's custodianship of the caves but Lex believes his father is behind it. Dr. Walden says he is on the verge of a major breakthrough and Lex gives him three days to show results before he fires him.
Clark returned to the caves and put the key from his spacecraft into the identically-shaped impression in the cave wall. A burst of energy shoots through Clark, lifting him into the air. When the beam stops, Clark collapses. Once again, Lex discovered Clark under unusual circumstances and shakes Clark awake, as he was disoriented. Dr. Walden appears and asked Clark how he got past the guard. When Clark left the caves, Dr. Walden told Lex that Clark surely knew more than he admits.
Later Lex found Clark's crumpled drawings of Kryptonian symbols in the blanks for "father" and "mother," and shows it to Dr. Walden, who doubts that Clark could have deciphered the symbols. Lex shows him a photograph of the burned barn on the cover of the Smallville Torch but Dr. Walden says it's a hoax. Lex insists that something happened to Clark and tells Dr. Walden to work with him, saying he might be the Rosetta Stone he needs to decipher the language.
Dr. Walden returned to the caves and finds the key wedged sideways in the wall of the cave. He pried it out and also put it in the slot. Clark arrives to see a burst of energy throw Dr. Walden back and when he rushes over to revive him, he quickly pockets the key. The resulting burst of energy short-circuited his cerebral cortex and put him into a coma.
Dr. Walden is taken to the hospital completely catatonic, with cataracts over his eyes. Doctors declared him catatonic due to a sort of "information overload" and predicted that he would probably not recover. Dr. Walden was transferred to Belle Reve.
When Clark's ship began to broadcast a Kryptonian message, at which time Dr. Walden's brain functions normalized and he woke up. Also able to hear the message, he kept repeating the phrase "The day is coming." He continued to slowly improve, now walking around, muttering the same phrase over and over. His cataracts have faded over the course of a day.