M. Vasalis (13 February 1909 in The Hague – 16 October 1998 in Roden) was a Dutch poet and psychiatrist. M. Vasalis is the pseudonym of Margaretha Droogleever Fortuyn-Leenmans. Vasalis is her Latinized maiden name.

Vasalis studied medicine and anthropology at Leiden University and in 1939 established herself as psychiatrist in Amsterdam. Later she worked in the same function in Assen.

Vasalis made her debut in 1940 with the collection 'Parken en woestijnen' (‘Parks and Deserts’). Her other poetry collections are 'De vogel Phoenix' (‘The Bird Phoenix’) from 1947 and 'Vergezichten en gezichten' (‘Views and Faces’) from 1954. Vasalis wrote some essays and a short story. Vasalis' work has been awarded multiple times.

She wrote traditional poems that were often characterized by the use of personification and anthropomorphism. Her poems often, after a series of nature impressions, end in a self-reflection.