- "These eyes have looked upon Pharaohs, and the son of the carpenter. And now, they must look at you, proudly showing me your idea like a child with a handful of its own excrement. I have never known humiliation, failure, or obscurity. How does it make you feel? Like coming home, I imagine."
- ―To Nick Cutler[src]
Mr. Snow was an ancient vampire, over 3000 years old, and the leader of the Old Ones. He had rotted teeth, was much stronger than younger vampires, and his skin was unnaturally pale with black veins visible beneath.
Mr. Snow was born circa 1000 BC. According to Hal Yorke, Snow was one of the earliest vampires, and nearly all vampires' bloodlines of recruitment can be traced back to him. Mr. Snow claimed to have met Egyptian Pharaohs and Jesus Christ, and to have never once felt any failure or humiliation in his life.
Mr. Snow's last visit to Britain before 2012 was in 1779; vampires took him to a village, where they massacred all the adults and used their bodies as a tableau of the vampire race's history, and then made the children of the village sing to them before they "made wine from their blood." Snow reminisced that he'd been highly touched by this particular tribute to him. (The War Child)
In 2012, Mr. Snow and the other Old Ones travelled on a freighter driven by a human crew from Bolivia to Barry Island, Wales across the Atlantic Ocean, to discuss their plans for a global vampire takeover. At at least one point during the journey, Mr. Snow blackmailed the freighter's human captain into leaving a young janitor locked out for Snow to drain. (The Old Ones) Mr. Snow also had a werewolf agent in Barry for the Old Ones, Milo, secretly watch over Honolulu Heights and the residents, among which were Annie Sawyer and the prophesised War Child Eve Sands, until the former and the other Old Ones arrived. (The War Child)
When the Old Ones finally arrived at Stoker Import and Exports at Barry, Mr. Snow found no-one there to greet them. (Making History) Shortly afterwards, Mr. Snow met with Milo and discussed the matter of the Honolulu Heights residents with him. Nick Cutler, who was meant to welcome the Old Ones, later arrived and tried to impress them, but Mr. Snow was bored and unimpressed at Cutler's failures and dismissed him.
Later, Tom McNair arrived and offered Eve to Mr. Snow on the condition that the former stayed with Eve. Snow apparently considered raising Eve himself, before Hal and Annie arrived and the latter angrily fended off the other Old Ones to get Eve back. Mr. Snow then returned Eve to Annie and decided to instead let Annie raise Eve herself and ensure that Eve stayed alive; confident that Annie would be unable to allow Eve to die despite the fact that this would negate the Skin Parchments' prophecy and allow the vampires to take over from humanity. However, Annie instead used Hal's explosives to blow up Stoker's, killing the Old Ones and Mr. Snow before the latter could stop her. (The War Child)
In an alternative timeline where Mr. Snow and the Old Ones weren't killed when they came to Britain in 2012, their plans to take over the world from humanity weren't stopped. On 11 April, 2012, Mr. Snow personally drained and killed the British Prime Minister on national television while the Prime Minister was appealing for calm.
After the vampires took over, as Eve grew up, Mr. Snow had the vampires secretly ensure from behind the scenes that she stayed alive. Snow had one notable encounter with Eve on 10 April, 2022, when interrogating Isaac Daniels after he and Eve were captured by the vampires. Mr. Snow learned from the interrogation who Eve was and killed Isaac, but allowed Eve to escape and had his forces ensure that Eve reached the human resistance's custody. (the War Child)
Mr. Snow was outwardly sophisticated, warm and soft-spoken, but underneath this thin exterior was an incredibly ancient, psychopathic, rotted and evil vampire. While Snow was very polite, sweet and respectful to strong fellow Old Ones and to those he considered true legends, he commanded respect, fear and obedience from other vampires, and terror of what the consequences of getting on his bad side or failing to appease him could be. He was known to often quietly speak with a very poetic yet dark and twisted way for words, and to have a sardonic sense of humour. Mr. Snow was almost always incredibly calm, laid-back, collected and confident; but when he failed to foresee Annie sacrificing Eve and killing him, Snow's usual collected and unthreatened demeanour fractured to a flash of pure fear and denial at his downfall, showing his fear of death alone.
As one of the oldest, if not the oldest, vampire, Mr. Snow was much more powerful than any vampire shown in the series.
- Vampire Mind Control - Mr. Snow had a hypnotic influence over younger vampires, which allowed him to force them to do what he wanted them to just by telling them to.
- Super strength - Mr. Snow was shown to be very strong, as he was able to rip out a human's internal organs with practically no effort.
- Immunity to cross - Unlike younger vampires, who are repelled by religious symbols, Mr. Snow was completely unfazed by said symbols such as crosses.
- Ability to enter private residences without permission - Though Mr. Snow never demonstrated this, it is held to be a feature of Old Ones that they could enter a human/werewolf's home without permission and not suffer any of the ill effects that younger Vampires do.
- In The War Child, Mr. Snow's teeth appeared to be less rotted in some scenes than in others.
- According to Mark Gatiss, Mr. Snow is just a nickname given to him by the other vampires, as there is no-one alive in the present who knows Snow's real name.
- Regus stated in Eve of the War that the very first vampires were two brothers who made a pact with the Devil to have immortality in exchange for blood. Due to Mr. Snow's advanced age and Hal's statement that he is "one of the first" and the progenitor of the majority of vampire lineages in modern times, some fans believe that Snow may have been one of these two brothers. However, other fans have discredited this, as Regus also mentioned that the original two vampires were Asian, whereas Mr. Snow is Caucasian; and have suggested that Snow may have simply been one of the vampires that the two original Vampire Brothers subsequently recruited, or that Snow may not have been recruited by the Brothers at all.
- Hal's vampire bloodline is apparently part of the majority that Mr. Snow started, as Snow was able to influence Hal with commands.
- Because of Hal's statement that all vampire bloodlines originate from Snow, he can be considered indirectly responsible for everything that happened on the show.
- Though never officially stated, Heggeman has been labelled by some viewers as the Syfy counterpart of Mr. Snow; although the character of Heggeman was introduced before Mr. Snow was conceived.