He appeared as the main antagonist in the Season 6 episode "Trespass".
He was portrayed by Jordan Belfi.
Mack was hired by Lex Luthor to guard his fiancé Lana from the hounding paparazzi. While guarding her, he became obsessed with her and began stalking Lana.
One night, Mack photographed Lana in her bedroom on his cellphone and sent the photo to her anonymously.
For her safety, Lana went to spend the night with Chloe Sullivan at the Talon apartment but Mack had followed her. Hearing a noise, Lana went downstairs to find a wrapped present with a negligee in it and an note that read "I want you to wear this... when I kill you."
Frightened, Lana tried run out of the exit door, but was accosted by dozens of paparazzi who forced her back inside. Brady, the head of security, escorted her back into the apartment just as Chloe arrives back home, also escorted by Mack.
Following this, Lana left the Luthor Mansion for her own safety, deciding to hide out at the Kent Farm. Brady and Mack took her to the Kent Farm and secured the house and the farm. Being part of Lana's security detail, Mack was able to continue stalking her.
Brady remained outside the door to Clark Kent's bedroom where Lana was staying. Mack sent Lana a threatening phone call while she was hiding in Clark Kent's bedroom. The caller said in a distorted voice that she can't hide and Lana noticed a puddle of blood seeping under the door.
Brady didn't answer when she calls and Lana opened the door to find that Brady had been killed. She was then startled by the flash of a camera and fell down the stairs. Lana was taken to Smallville Medical Center after her fall, but Mack once again sent her a threatening call.
Dr. Langston reports that Lana and the baby are fine and tells Mack to move her to an older wing of the hospital to secure her safety.
As Lana explored the dilapidated old wing of the hospital, she was suddenly ambushed by a photographer who began taking multiple pictures of her. Clark arrives just in time to throw the photographer across the room.
Mack finally appears and carts him away. Clark helps Lana up when they hear a gunshot. Mack claims that he had a hidden weapon and he had no choice but to shoot him.
Thinking the ordeal is over, Mack takes Lana back to the Luthor Mansion. He tells her that Lex's flight is delayed due to the weather and Lana thanks him for protecting her. Mack muses that Lex shouldn't have left her alone.
Lana asks him to tell the staff to bring her something to eat and he reports that he has sent all the staff and the rest of the security team home so they wouldn't get caught in the coming snowstorm.
He remarks that it was something Lana would do because she is good and kind, unlike Lex's other girlfriends. Lana is unnerved by his audacity, but he then reveals that he watches her every day.
Lana realizes that Mack is the stalker, but she gains his trust by admitting that she didn't know what she was getting into with Lex.
Mack goes to comfort her and she smashes a glass bottle on his head and runs away. Deciding that Lana was beyond saving, he attacked her directly. She tries to call for help, but Mack has cut the phone lines. He breaks into the bedroom and she escapes out the window. Lana ran from Mack who chased her with a battle-axe mounted on the wall.
He pursued Lana up onto the roof and attacked her, but the two of them fall through the skylight. Mack dies upon hitting the floor, but Lana is saved when Clark arrives in the nick of time to catch her.