In the Netherlands, it’s either “Jan Smit” (both a very common first and last name, but also a local celebrity’s name) or “Henk de Vries” which IIRC is the most common name here.
I also vaguely remember some old Dutch forum naming everyone Henk de Vries by default.
I like the contrast with this comment about how web is starting to do too much. I agree with both sentiments, so it would be great to find the golden mean.