Llanychan is a parish near Llandyrnog, Denbighshire, Wales. The parish consists of 567 acres (2.29 km2), and is the smallest parish in the diocese of St Asaph. The parish stands approximately three miles north-east of Ruthin.
There are only two churches in Wales consecrated to Sant Hychan, Llanychan church, after which the parish is named, is one of these. The church is mentioned to in the Norwich Tax Records in 1254. Notable features include a window dating from 1626, a reading desk from 1730 and a reredos from 1846, the church was restored extensively in 1878.
There was a school in the parish until the beginning of the 20th century.