Sea Monkfish (Angler) Lophius piscatorius
This is a very distinctive fish, recognizable by having its head and body depressed, a wide mouth, broad head and a fleshy 'lure' at the end of its first dorsal spine, which is used to attract prey. Its colour can be variable but is principally brown or greeny brown with reddish or dark brown mottlings. Image: Poul Erik Rasmussen (iNaturalist).
Find out more: iNaturalist, Marine Life Information Centre