'Muscular' was a British three-part naval operation, together with 'Prefix I' and 'Prefix II', against German shipping plying the routes along the west coast of German-occupied Norway (24/29 March 1945).

'Muscular' took the form of a night attack in the Leads between Stadlandet and Bredsund, and the forces under the command of Rear Admiral R. R. McGrigor were the escort carriers Nairana, Puncher, Queen and Searcher, the light anti-aircraft cruisers Bellona and Dido, and the destroyers Carysfort, Onslow, Serapis, Zealous, Zest and Canadian Haida and Iroquois.

The British sea and air effort found no sizeable shipping for attack, but two carrierborne fighters attacked merchant ships and minesweepers. A counterattack by between six and nine Messerschmitt Bf 109 fighters resulted in three being shot down by Grumman Wildcat fighters from the escort carriers and another two being damaged.