Olive Woolly Bugger: This is one of the best flies known to man and the ultimate streamer. It is great for Bass, Carp, Salmon, Steelhead, and Trout. Fish it dead drift or strip it. Always a go-to fly! Based from the Palmer which is one of the oldest of flies.
Swing it - river, Strip it - works great in lakes.
Fish it deep and strip it up in lakes for big trout.