Willem is a seasoned music composer, who has written music for many multiple award-winning productions, including many feature films, television series and documentaries for international clients such as Netflix, Amazon prime, National Geographic, Discovery, Smithsonian
| Movie | Lions of Crocodile River | 2007 |
| Movie | Cheetah Blood Brothers | 2007 |
| Movie | My Father's War | 2016 |
| Movie | Lion Brothers: Cubs to Kings | 2019 |
| Episode |
Stories of Africa Cheetah: Race to Rule |
2013 |
| Movie | Blood Rivals Lion vs Buffalo: Buffalo Fortress | 2014 |
| Movie | Predators of the Savuti | 2023 |
| Episode |
Stories of Africa The Real Lion Queen |
2013 |
| Movie | Lien se Lankstaanskoene | 2012 |
| Movie | Lion Army | 2009 |