The St Kilda house mouse (Mus musculus muralis) is an extinct subspecies of the house mouse found only on the islands of the St Kilda archipelago of northwest Scotland.

[1] They were first described, alongside the St Kilda field mouse, by natural historian Gerald Edwin Hamilton Barrett-Hamilton in 1899.

Isolated on the islands, the St Kilda house mouse diverged from its relatives.

It became larger than the mainland varieties, although it had a number of traits in common with a subspecies found on Mykines in the Faroe Islands, Mus musculus mykinessiensis.

[3] When the last St Kildans were evacuated in 1930, the endemic house mouse became extinct very quickly,[4] as it was associated strictly with human settlement.