The Pheasant Leech
This is based on a Ross Mueller pattern, which used turkey marabou. As hunters, my brother and I had ringneck pheasant skins available, and discovered that pheasant is an excellent substitute. The video below shows many good brown trout caught on this fly -- most caught by my brother. (I swear he only takes me along to have a camera man.) But I've done well on this one, too. If my life depended on catching a trout over 16 inches from an Iowa stream, this is the fly I'd attach to my tippet.