The Once-ler is the narrator of The Lorax. He is a greedy industrialist who cut down all of the beautiful, multi-colored Truffula Tree to make a peculiar garment known as a Thneed, 'a Fine-Thing-That-All-People-Need'.
There are roughly one-sh*t billion tropes so PLEASE look through them before adding one. Otherwise add what you like. ADDITION: PLEASE read through the trope description provided before submitting something. It's not a huge deal but too often people submit characters that don't fit just because they misinterpreted the title...