Seán Ó Catháin (fl. 1726) was an Irish scribe. Little is known of Ó Catháin. He transcribed – by Seathrún Céitinn – and , "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 Furbogh, County Galway) in 1726, now BM Egerton 184. He wrote RIA 23 G 4, containing history, genealogy and poetry, sometime between 1722 and 1729.