thumb|Spire of Our Lady Queen of Peace church in Coosan
Coosan () is a townland and suburb north of Athlone, County Westmeath in Ireland. Coosan, which is situated on the shores of Lough Ree, is surrounded by water on three sides and bordered by Athlone on the fourth. The Lough Ree Yacht Club is located in the area.
The area includes a number of townlands, several of which are described 'quarters'. These include Castlequarter, Hillquarter and Meehanquarter.
Notable people
- Ray Connellan, Gaelic footballer and Australian rules footballer
- Dessie Dolan, Gaelic footballer
- Lisa Dwan, actress
- Robbie Henshaw, International rugby player