Renate Magdeleen du Plessis (born 14 July 1981) is a South African former competitive swimmer who specialised in butterfly events.

Du Plessis made her official debut at the 1997 Pan Pacific Swimming Championships in Fukuoka, Japan, where she established a South African record of 1:02.10, but finished fourth in the 100-metre butterfly.

[7] At the 2000 Summer Olympics in Sydney, Australia, Du Plessis competed for South Africa in the women's 100-metre butterfly, along with her teammate Mandy Loots.

Missing out of the Olympic Trials, she finished behind Loots from the Mare Nostrum Swim Meet in Rome, Italy with a FINA A-standard time of 1:00.66.

Coming from fourth at the initial turn, she faded down the stretch with fatigue and slow pace to pick up a fifth seed in 1:01.32, more than half a second (0.50) below her entry standard.