Roger Decock (20 April 1927 – 30 May 2020) was a Belgian professional road bicycle racer.

Decock won Paris–Nice in 1951. During the 1951 Tour de France he was having the best Tour of his career and was 5th place overall when he became the only witness to one of the most infamous moments in cycling history. Wim Van Est was defending the Yellow Jersey; he was descending the Col d'Aubisque when he lost control of his bike and went off a cliff. Decock was the only person to witness this and he stopped to get help for the fallen rider. It took several minutes to locate Van Est and over two hours to rescue him from 200 feet down the mountain. In total, Decock waited 25 minutes until it was clear the situation was in hand, but the time he waited cost him his high place and he ultimately finished the Tour in 17th.

The following year he had the biggest victory of his career when he won the 1952 Tour of Flanders. As the finish line approached, Decock, Loretto Petrucci and Briek Schotte, one of the best riders of his generation, were the three lead riders fighting for the win and he defeated them in the sprint. Wim Van Est finished 4th.