Essex Miniatures - a little long in the tooth, the dumpy 25mm may lead to them looking unintentionally comical. Perhaps they could be a secretive halfling ninja clan?
Foundry have re-released some real classics by Aly Morrison, which some of you may recognise from back in the day.
Privateer Press have the Skorne who could perhaps be some form of oni or bakemono.
As an aside, this should probably be No. 4 in the series of OA mini posts. I seem to have mislaid No. 2...