Killelan, whilst formerly a parish in its own right, did not have any single developed settlement. Its built environment consisted of numerous small farms with a few other enterprises such a mill and smithy, with the parish church providing a religious focus for the community.
Following the amalgamation of the Houston and Killelan parishes, the parish church - dedicated to St Fillan fell into ruin, but is now a scheduled ancient monument. More information can be found in the Killelan cache.
The name of Killelan derives from the Scots Gaelic term for 'cell' or 'church' of Fillan as a result of the dedication of its former parish church.
Killelan or Killalan is spelled somewhat differently with usage remaining inconsistent. 'Killelan' is used by both the modern Gazetteer for Scotland, the Church of Scotland and the Community Council, whilst 'Killalan' is favoured in the 18th and 19th century Statistical Accounts.