Saint Erasmus of Formiae was a Christian saint and martyr who died c. 303, also known as Saint Elmo. He is venerated as the patron saint of sailors and abdominal pain. St Erasmus or Elmo is also one of the Fourteen Holy Helpers, saintly figures of Christian legend who were venerated especially in Central Europe as intercessors.

The Acts of Saint Elmo were partly compiled from legends that confuse him with a Syrian bishop Erasmus of Antioch. Jacobus de Voragine in the Golden Legend credited him as a bishop at Formia over all the Italian Campania, as a hermit on Mount Lebanon, and a martyr in the persecutions under Eastern Roman Emperor Diocletian.

When the persecutions of the Emperor Diocletian began,

Then came the Western Roman Emperor Maximian who, according to Voragine, was "much worse than was Diocletian." Erasmus would not cease preaching the Gospel, even though he was "put into a pan seething with rosin, pitch, brimstone lead, and oil, [which were] pour[ed] ... into his mouth, [from] ... which he never shrank." A searing hot cloak and metal coat were both tried on him, to no effect, and an angel eventually carried him away to safety."