Nick Willemse is a Dutch self-taught cartoonist and comic artist, who works under the pen name Niwi (and previously also as Niwi Ruimtekiwi). He published his first work in small press comic magazine De Stripper between 1998 and 2003. He then started his online daily comic 'Dr. Saterpluis', of which he also self-published a book collection in 2003. He participated in several issues of the small press comic magazine De Lijn and in the comics project 'Teken Mijn Verhaal'.
Rotkopf, published on the online platform Stripster in 2009
He makes comics for a host of commercial clients, such as Triaspect, Telenet, Kookjij.nl and the auction sites Biedplaats, Epaloe and LavoroFatto. His most notable commercial comic is 'Inkooptopper', about the corporate world of acquisition, which he makes for a knowledge platform for purchasers. Book publications have appeared since 2013, and part of the proceeds are donated to the CliniClowns Foundation. Since 2014, Niwi also makes the youth's comic 'Camping Het Hijgend Hertje' for P@per, the companion publication of the Flemish Brabant Strip Magazine. He regularly publishes autobiographical comics online.