Saint Dominic ( Spanish : Domingo ) , ( 1170 â `` August 6 , 1221 ) was the founder of a Catholic religious order , the Friars Preachers , often called the Dominicans or the Order of Preachers ( OP ) . Saint Dominic , also known as Dominic of Osma , often called Dominic de GuzmÃ n and Domingo FÃ lix de GuzmÃ n ( 1170 â `` August 6 , 1221 ) was the founder of the Friars Preachers , popularly called the Dominicans or Order of Preachers ( OP ) , a Catholic religious order .