A very simple, universal, shrimpy kind of woolly bugger like hackle fly
The White was originally tied by Danish angler Rasmus Hansen. Rasmus earned the nickname "The Fork" in my circle of anglers because he once wrote an article about turning fork handles into lures for spinning.
These days Rasmus is almost exclusively a fly angler, mostly known for his pike fishing and his trips to Lapland in Northern Sweden. But he does often fish the coast for sea trout, and I personally meet him now and again when I roam the Northern coast of the Island I live on.
He also used to write for the same Danish angling magazine that I do, and we have met on many an editorial summit - often memorable because of the good company and the fishing, but of course also for slight dozes of serious editorial work - but that's a whole other story.
Rasmus himself tells the story about The White - or The White One as he calls it - on his home page. The fly stems from 1993 and has since been refined and forked out to other patterns, but the original tie is still a stable pattern in Rasmus' flybox, He uses it as a provocation (read: attractor) or as a shrimp imitation, and prefers it for turbulent water and autumn fishing.