Recorded in the spellings of Scadden and Scaddon, this is an Irish surname, for which a claim is made that it is not Irish! It is not often the the famous Irish etymologist Edward MacLysaght denies a name as being Irish, but in this case he says that although (quote) "it is on record (in Ireland) since 1299, when an entry is in the Justicary Rolls records that one Martin Scadan was concerned in a Tipperary trespass case..... that in no instance does the prefix O' occur with this name". He claims that in medieval times "virtually" all Irish names had an O' or Mac prefix. However he does concded that the Old Gaelic word for a herring was "scadan", and we suggest that just as the English word "herring" also became a surname for a herring fishermen or merchant, Scadden in its various spellings was the same. Certainly there is no contradictory evidence, and nothing to suggest that the name is English, there is even a place in Tipperary called Scadanstown. After the British "conquered Ireland in 1170, they did not encourage the Irish to fish, and it may be that in consequence this name lost its reason for existence, and the early nameholders moved inland to Tipperary. Early examples of the name recording in addition to Martin Scadan in 1299 include Teag Scaddan, a member of a jury, also of Tipperay in 1312.