Glen Mackenzie (グレン・マッケンジー, Guren Makkenjī?), a 72-year-old man, and his wife Martha Mackenzie (マーサ・マッケンジー, Māsa Makkenjī?) are an elderly couple who emigrated from Toronto, Australia to Fuyuki City, Japan over forty years before the Fourth Holy Grail War.
Glen was a "hotshot businessman" who moved his family to Japan as part of his job over forty years ago, but he decided to live in Miyama permanently after becoming taken with the city. When deciding to live out the rest of their lives there, Martha requested two things from him, that their house be built on a hill in Miyama and that there be a skylight that allowed easy access to the rooftop. Retiring from his company and starting his own independent import-export business, he had great management ability, but lacked ambitions as a trader. He worked for forty years while avoiding pitfalls and bankruptcy, and he managed to pass the company to a successor once he had saved enough money. He began spending his time in quiet tranquility while working part-time as a teacher at an English conversation school.
Their son Chris was in elementary school when they moved to Japan, and he eventually started a family there. While he enjoyed the country, he felt a strong attraction to his roots and wished for his son to be educated in Australia. When his son was ten, his family moved back to Toronto and gradually fell out of contact with his parents. It came to the point where they barely heard from each other at all, and it eventually became ten years since they had received a single letter or a visit from the family.
Waver Velvet, needing to use a fake identity to cover himself in the Fourth Holy Grail War, sought out the couple after learning they lived alone in order to also avoid having to spend money on a hotel. Getting information on them through hypnosis, he deceived them with suggestion magecraft into making them believe he is their grandson, "Waver Mackenzie", through transfiguring their own impression of their grandson onto his own image. He made them believe that he was visiting while studying abroad in England.
Glen and Martha find Japanese culture appealing, although they were baffled by the difference between futons and beds when they first arrived. Although Martha is scared of heights and never joins him, Glen greatly enjoys the view of the sunrise from his rooftop, believing there to be no better view. Although he likes the country, he feels regretful if that was the reason why contact has been severed with his son and why Martha never smiles, and he dreams of sitting on the rooftop with his grandson. He believes that wish will never come true due to the facts that the grandson had never done so when he lived in Japan and that he has never contacted them since leaving.
They are very kind to their "grandson" under the suggestion spell, allowing him to board there and even let Rider stay there without question after befriending him. When the spell is lifted, Glen is not truly angry, and he is appreciative of the fact that the experience has brought a smile back to Martha's face.
Upon the day of summoning Rider, Glen and Martha greet Waver in the morning, baffled by the chickens that Waver has brought for the ritual. As he explains it away and prepares to leave, they warn him to be careful about the town due to the recent famous serial killer being active again. Later on a few days after the first scuffle of the Holy Grail War, Rider, who had been staying away from the couple in spiritual form, "visits" the house as a friend of Waver. He quickly befriends Glen, starting to drink beer with him, and charms Martha with his compliments. Waver decides to pass Rider off as someone he met abroad who decided to make an unannounced visit, and they offer to let him stay.
Later after Waver and Rider battle Saber, Waver wearily returns to the household in the early morning, and Glen calls him up to the rooftop where he had been sitting for a long while while waiting for Waver to return. Strangely adamant about it, Waver concedes to the request. He pretends to reminisce about when he and his grandson enjoyed the view while being sorrowful over being separated from his son, and then reveals to Waver that he knows that Waver is not his grandson after the spell unknowingly came undone. Although baffled by the reason as to why they believed Waver, he simply passes it off as one of the world's many unexplained phenomenon. He remains very calm at the revelation, and he does not even try to have Waver explain himself. When Waver asks if Glen is angry, he responds "of course", but feels Waver's behavior is gentler than his own grandson and feels that there was no ill-intent in Waver's actions. He believes both Waver and Alex possess a rare straightforwardness lacking in younger people, and he doesn't even wish to understand their reasoning for them deceiving the couple.
Glen decides to ask Waver to stay, hoping to keep the relationship going for a while longer, especially when Martha has yet to notice anything strange unlike himself. He describes the time spent with his "grandson" their "hard-sought treasure." Waver reveals that he cannot promise even being able to return, and Glen is able to deduce that they are risking their lives. Glen tells Waver that there is nothing more important than looking back over life after having lived through it, stunning Waver speechless as to how the notion is contrary to gambling his life away. The Holy Grail War ends that day, and Rider is killed by Gilgamesh. Waver remains alive and returns to the Mackenzie household, and their breakfast feels empty without Rider, who Waver mentioned went back to England due to an urgent issue. As they watch the news about the destruction caused by the Holy Grail, Waver asks them to allow him to continue to stay with them for a time so as to see the outside world. Martha is extremely happy and compares the notion to something Rider would have said, and Glen and Waver exchange a trusting look between each other.
 Fate/Zero material - Encyclopedia: Glen Mackenzie [Person's name], p.094
Glen Mackenzie [Person's name]
A 72 year old man from Australia. Thanks to hypnosis, Waver was able to use him for free room and board during the Fourth Holy Grail War.
In his younger days he was a hotshot businessman, and moved his family to Japan as part of his job. However, he ended up being so taken with Fuyuki that he decided to live there permanently. He retired from his company and started up his own independent import-export business.
But though his management ability was solid, he had no great ambitions as a trader. He worked for forty long years, avoiding pitfalls and bankruptcy, and passed the company on to a successor as soon as he had enough money saved. Now he passes his days in quiet tranquility, working part-time as a teacher at an English conversation school.
His son Chris had been in elementary school when they moved, and while he enjoyed life in Japan he also felt a strong attraction to his roots and wanted his son to be educated in Australia. In the end, Chris' family moved back to Toronto soon after the birth of their child and gradually fell out of contact with Glen and his wife, until eventually they barely ever heard from each other at all.
- Fate/Zero - Volume 4
- Fate/Zero - Volume 1
- Fate/Zero - Volume 2