Altarnun (/ˌɔːltərˈnʌn, ˌɒl-/ AWL-tər-NUN, OL-; Standard Written Form: Alternonn) is a village and civil parish in Cornwall, England, United Kingdom.

It lies 7 miles (11 km) west of Launceston[2] on the north-eastern edge of Bodmin Moor[3] at grid reference SX 223 811.

[8] The moorland area of the parish is large and lies west of the village towards Rough Tor and southwards towards Dozmary Pool.

The village is in the valley of the Penpont Water and the parish is divided by the A30 trunk road which passes close to Fivelanes, once an important stopping place for stage coaches.

)[14][15] Altarnun features in the novel Jamaica Inn by Daphne du Maurier, set in the parish's former coaching house by the same name.