| Petra Hillenius | |
| Fullname: | Petronella Angela "Petra" Hillenius |
| Nationality: | Dutch |
| Birth Date: | 7 February 1968 |
| Birth Place: | Woerden, the Netherlands |
| Death Date: | 27 March 2020 |
| Show-Medals: | yes |
Petronella Angela "Petra" Hillenius (7 February 1968 in Woerden[1] - 27 March 2020) was a Dutch breaststroke swimmer, who competed at the 1984 Olympics in Los Angeles.[2] She finished 19th in the 100 metre breaststroke and 18th in the 200 metre breaststroke.
In 2014, she became a board member of the Royal Dutch Swimming Federation.[3] She resigned the position when she was diagnosed with ALS four years later. In March 2020 she died due to ALS.[4]
She was a teacher for 24 years at the Hospitality Business School of the Saxion University of Applied Sciences.