Seán Ó Catháin (fl. 1726) was an Irish scribe.
Little is known of Ó Catháin. He transcribed Trí Biorghaoithe an Bháis - by Seathrún Céitinn - and Beatha Chaitríona, "air forálamh an óig úasail róonoraigh fhíorchartannaidh .i. Fhroinnsais Óig a Blake mhic Tomais oíghreadh na bForbach" (for Francis Óg son of Thomas Blake of Furbo, County Galway) in 1726, now BM Egerton 184. He also wrote RIA 23 G 4, containing history, genealogy and poetry, sometime between 1722 and 1729.