Bestselling author of the Boekenweek gift book

Hendrik Groen® stepped out of anonymity this week and is suddenly widely in the news as Peter de Smet.

He is the author of the Boekenweek Gift Book 2026, and the lawyers at the Merkplaats are extremely proud of that. Not only because of his literary success with more than 1 million books sold, but also because Hendrik Groen® has been a trademark registered by the Merkplaats since 2017.

Long before it became known who was behind the pseudonym, it was already clear how strong the name Hendrik Groen® had become as a brand. His diaries became bestsellers, his books were translated into more than 35 countries, and his character grew into a household name.
This example clearly shows how important trademark protection is. The name no longer refers only to an author, but has also gained commercial and reputational value.

For example, The Secret Diary of Hendrik Groen was a popular Dutch comedic drama series by Omroep MAX from 2017 to 2019. The leading roles were played, among others, by André van Duin (Evert), Kees Hulst (Hendrik) and Olga Zuiderhoek (Tine).

It can still be viewed on NPO Start.

A fun additional detail: Hendrik Groen® came to us through Kluun, the author of Komt een vrouw bij de dokter. Before 2016, there was speculation that Kluun himself was behind the pseudonym Hendrik Groen®. This turned out not to be the case, but the referral did lead to a successful collaboration and a formally registered trademark.

Now that Hendrik Groen® has publicly stepped forward as the author of the Boekenweek Gift Book Piaggio, it once again becomes clear how valuable a strong name can be. Fame can sometimes come unexpectedly fast, but trademark registration ensures that you are prepared for it.

The story of Hendrik Groen® shows that even a pseudonym can grow into a powerful brand. And those who register their brand in time are in a stronger legal position once success arrives.

Want to protect your own name, title or brand? Then contact us.