Firstly, Trier is a city, named for the tribe of Celts who founded it in the late 4th century BCE, on the border with Luxembourg today, and west of the Rhine (actually about as far west as you could go and still remain in the country of Germany), now considered Germany’s oldest city. The Romans conquered the Treveri and renamed the city Augusta Treverorum in 16 BCE. It was in the province of Gaul. The Franks seized the city from the Romans in 459 CE, and it became part of Francia, and later Eastern Francia, which correlates somewhat with the modern nation of Germany.
The region reflects the Celts, Latins, Franks, and Germanics who settled there, and the genetics of the people there can be correlated to these general people groups. People with the last name Trier can generally be traced to the city one way or another.
Interestingly, the most famous bearer of the surname, is not from there at all, and his surname actually comes from his stepfather. From an interview in the German magazine Die Zeit, 11/10/2005:
“You grew up with a Jewish father. On her deathbed your mother told you that, in fact, your real father was a descendant of the Danish composer J.P.E Hartmann. And that this was her way of securing a "creative genetic make-up" for her child.
Until that point I thought I had a Jewish background. But I'm really more of a Nazi. I believe that my biological father's German family went back two further generations. Before she died, my mother told me to be happy that I was the son of this other man. She said my foster father had had no goals and no strength. But he was a loving man. And I was very sad about this revelation.
Did the fact that you were more or less "bred" to be a creative son put you under pressure?
Oh yes. And you then feel manipulated when you really do turn out to be creative. If I'd known that my mother had this plan, I would have become something else. I would have shown her. The slut!”
From Visual Authorship: Creativity and Intentionality in Media also published 2005:
“...Trier, the person, is a project realized by his mother, Inger Høst (1915-89). In 1989, when his mother was dying, she confessed to him certain facts about his existence, which made him realize that he himself was the result of a plan. The mother confided that Trier's late father, Ulf Trier (1907-78), was not his real father. The mother got pregnant with her boss at the Ministry where she worked, and he was a man, she confessed, whom she had chosen to be father of her child because he had "artistic genes". Evidently, she wanted a child who could realize her own artistic dreams… Thus Trier was a kind of artistic construction, a genetic project undertaken by his ambitious mother.”
Lars Von Trier later added the signifier ‘Von’ to mock the Austrian practice that distinctified nobility. Coincidentally, there are 7 people using the surname ‘von Trier’ worldwide. ‘Van Trier’ on the other hand, has an incidence of nearly 700. Generally the Dutch ‘van’ simply means ‘from’, whereas the Austrian ‘von’ was added to someone’s name if the bearer was granted it by the nobility.
So the most notable bearer of the Trier surname, is not a Trier at all. The filmmaker is notable for being provocative, and so many of his films transgress various norms, depending on the culture. I personally have not seen very many, certainly not most, but I will say, AntiChrist and Dogville are surprisingly coherent in their admission of human nature, and leave a lasting impression.