Nicholas Conroy, also known as The Traveler, was the uncle of Sarah Conroy and the main antagonist of the Season 3 episode "Slumber" of Smallville.
Nicholas was portrayed by Christopher Shyer and The Traveler was portrayed by John DeSantis who portrayed the Male Zoner Companion in the same series, The Juggernaut in Thir13en Ghosts, the Bald Man in the TV series A Series of Unfortunate Events, Moonface in Incident On and Off a Mountain Road and voiced Ollie in Barbie and the Magic of Pegasus.
Nicholas Conroy gained custody of his niece, Sarah, after her parents died in a car accident and became the executor to Sarah's inheritance. In order to control her finances, Nicholas kept her in a permanent vegetative state. However, due to exposure to green meteor rocks, Sarah had developed the ability to communicate with people through their dreams.
To outward observers, he seemed like the devoted uncle caring for his sick niece. In her dreams, she envisioned her uncle as a monstrous entity cloaked in a blood red robe, extremely tall with bony, decayed fingers wearing a red cape with a tattered hood and calling itself the Traveler. When Sarah was close to waking up, a dream version of himself called the Traveler would prevent that.
Sarah first met Clark at Crater lake but vanished underneath the earth. Clark again saw her at Smallville High and tries to ask her what's going on, but she just says that "he's" always after her. She starts to look terrified and Clark sees the reflection of a red hooded figure in the glass of the case. However when he turns around, no one is there but Pete, and Sarah having disappeared as well.
At the Kent Farm Clark saw Sarah again and tells him that lilacs are her favorite flower and begs him to not let The Traveler take her again. Suddenly the Traveler appeared through smoke and Clark approaches the Traveler but he simply throws him across the yard, declaring in a deep distorted voice that Sarah cannot hide from it. He engulfs Sarah and Clark runs to rescue her but has vanished and Clark awakens from the dream he had been in for a day and a half.
Clark recognized Sarah's presence in his dreams as a cry for help so he and Lana began investigating Sarah's circumstances. They went to visit her but were dismayed to learn that Sarah was in a coma being cared for by her uncle, Nicholas Conroy. Clark noticed the lilacs in her room and says that they are her favorite and also noticed Nicholas wears a St. Christopher's medallion, the patron saint of travelers.
Nicholas was unnerved by Clark's observations and excuses the two, saying he has to administer Sarah's medication. After learning that there was no medical explanation for her coma, they deduced that she was being unnaturally kept asleep by her uncle with intravenous drugs.
He is visibly tired and as soon as Lana leaves to get him a cup of coffee, he drifts asleep. Sarah appears in his dream and explains that this is the first time she's been able to enter dreams and could hear them when they came to visit. He asks who the Traveler is but she avoids the question. She reveals that every time she starts to come awake, her uncle gives her something that pulls her back asleep. She then falls off the balcony and is engulfed by the Traveler.
Clark later returned to Sarah's house and asked Nicholas if he can sit with her for a while. He X-rays the medicine cabinet and steals one of the vials of medicine before super speeding away. Nicholas discovers the open cabinet and looks angry. Clark drives home in a hurry but Sarah appears in the seat next to him saying that Nicholas is angry.
Sarah was able to use her power to enlist the aid of Clark Kent in exposing her uncle's schemes and reviving Sarah from her coma.