The Mussau Monarch is a monarch flycatcher recorded on Mussau (St Matthias) Island, Papua New Guinea. Its 1902 description was based on one bird collected there.
The 1902 type specimen was in heavy molt and still had some juvenile feathers. It appeared almost white, with a black forehead, throat, and eye-ring, and white tips on the outer tail feathers.
The species profile describes it as a forest bird that gleans small invertebrates from branches.
An extinction-risk assessment has not been added yet.