Fidelis of Sigmaringen was a 16th-century German Capuchin friar and missionary who played a significant role in the Catholic Counter-Reformation. Born Mark Roy in Sigmaringen, he initially studied law and philosophy, eventually practicing as a lawyer known for his integrity and support of the poor. Seeking a more spiritual life, he joined the Order of Friars Minor Capuchin, receiving the name Fidelis. He was later sent to preach in the Graubünden region, where his successful efforts to convert people to Catholicism led to intense opposition from local Calvinists.