Fermin was a legendary holy man and martyr, traditionally venerated as the patron saint of Pamplona, the capital of Navarre, Spain. His death may be associated with either the Decian or Diocletianic persecution.
Although he is said to have lived in the third century, Fermin's legend is a creation of the ninth century. It probably originates in the diocese of Toulouse, which endeavoured to spread the devotion to Saint Fermin. If there was a historical Fermin he is wholly unknown and was probably no more than a name on a tombstone around which an edifying legend was crafted.
According to the legend, a senator from Pamplona named Firmus was converted to Christianity by Honestus and persuaded Saturninus to come to Pamplona to baptise him. There the bishop preached to large crowds and baptised some 40,000 people over three days. Firmus's son, Firminus, was entrusted to Honestus for his Christian education and at age 31 went to Toulouse to be consecrated by Saturninus's successor, Honoratus. Fermin then went to preach in northern Gaul, where he became associated with the city of Amiens. He was persecuted and ultimately martyred.