Dr. Langston was a recurring supporting antagonist in the Sixth Season of Smallville.
He appeared as a main antagonist in Lex Luthor's perspective in the episode "Promise".
He was portrayed by Fred Henderson.
After Clark as Kal kidnapped Lana and took her to his barn, Dr. Langston was summoned by Lex to checkup on her and gave her a clean bill of health. Lex met the doctor in the hallway and informed Lex that Lana's pregnancy was not "typical", but was progressing as scheduled.
When Lana was being stalked, she hid at the Kent Farm but accidentally fell down the stairs after an attempt on her life. Doctor Langston was called again to check on her and Langston assured Lana that the baby was fine.
He gave her an injection to sedate her and bring down her blood pressure, assuring her that it would not harm the baby. Langston suggested Mack that they can put her in the old wing of the hospital to secure her.
In reality, however, Lana wasn't pregnant at all. Langston had been secretly giving Lana synthetic hormones that simulated pregnancy, all part of a scheme by Lex to ensure that Lana would marry him and cut Clark Kent out of her life.
On Lex's wedding day, in the mausoleum beneath the church, Dr. Langston threatened Lex by claiming he would tell Lana everything about her "condition" if Lex didn't deposit two million dollars into his account.
He turned to leave when Lex flew into a blind rage and attacked the doctor. Lex beat him thoroughly causing Langston to fall back against a stone crypt, hitting the back of his head and died instantly. Lex then opened the crypt and hid the doctor's body inside it.
Lionel later meets Lex after the ceremony because he knows that Lex killed Dr. Langston. Lex offers him control of LuthorCorp or even Level 33.1 but Lionel just says he'll know when it's time to collect.
Lana later fainted and awoke in the Smallville Medical Center and Lex is forced to tell her that she's lost the baby due to complications. After the miscarriage, she asked Lex to call Dr. Langston, but Lex claimed he wasn't answering his pages. Lana wanted answers to explain her miscarriage, but she fell into a deep depression after she learned that Dr. Langston was killed in a car accident on the day of their wedding.
Lana later learned that her pregnancy was a fraud and never existed, she was shocked and confused. Her treating doctor informed her that instead of the prenatal vitamins she was told she was taking, they were actually synthetic hormones that simulate pregnancy. Langston's role was revealed as it was he who gave them to her.