The Salmon Man, also known as The Salmon Ghost, is an entity in Season 6. It's a invisible player or mob with a Salmon head on.
The salmon man is a unknown creature, who could possibly a hermit, but no one knows for sure. He travels around the world dropping sea-pickles everywhere he goes, every so often appearing in Hermits videos. He is fully invisible, except for his salmon-Mask that wears. He is also apparently the thing that built the giant salmon mask on Grians 'in a pickle store'.