Hammerthor are a brand of mens underwear based in Denmark, that have been in manufacture since 1893. I hear that they are responsible for Japanese-based Comme des Garçons' line of underwear, as well, some of which have their trademarked designs, and others that are simply rebranded. According to their website:

Back in 1893, when the original Hammerthor quality was established, following the latest fashion was not so crucial. In those days, customers were more concerned with quality.

As clothes were expected to last for many years, it was important that they were durable and practical. These basic principles are what we still live up to at Hammerthor

I discovered Hammerthor when I was researching underwear devoid of logos or the name of the brand on the elastic band. I bought them through oki-ni, who also stock some mouth-drooling pieces by Raf Simons and Jil Sander. So far they have proved to be pretty comfortable. Does anyone have any other recommendations?