Aleida Mathilde (Ada) van Keulen (13 January 1920, in Aalsmeer – 25 January 2010, in Laren, North Holland) was a Dutch woman who took part in the resistance during World War II.

On June 13, 1944, she was betrayed and arrested together with 27 other resistance fighters in Amsterdam.

Among others, they included Jo Hessels, Hendrik van Wilgenburg, and Joukje Grandia-Smits, all of whom were imprisoned.

She was sent to Vught concentration camp and in September 1944 deported to Ravensbrück.

On April 30, 1945, van Keulen was freed by the Americans during the Wolfratshausen evacuation march.