Na Fir Bolg is a folk music festival, held annually in Vorselaar, Belgium.

A few known groups who have played at Na Fir Bolg are: The Albion Band, John Kirkpatrick, Robb Johnson, Yevgueni, Bram Vermeulen, Mira, De Mens, The Popes and Anam.

Because all persons who thought of organising the festival were a bit fat, they called them self "the round men".

Na Fir Bolg is a non-profit festival, every year a charity is chosen to support.

In 2009 and 2010 they supported Catapa, an emerging volunteer movement in Belgium who are active in the fields of globalization (and how to change it) and sustainable development in Latin America.