Understanding the different wine professionals

Need help in understanding the different roles in the wine profession? Here are the most important roles.
Cooper: Maker of wooden barrels, casks, and other similar wooden objects.
Négociant: A wine merchant who assembles the produce of smaller growers and winemakers, and sells them under his own name.
Vintner: A wine merchant or producer.
Sommelier: A person in a restaurant who specializes in wine. They are usually in charge of assembling the wine list, staff education and making wine suggestions to customers.
Winemaker: A person who makes wine.
Oenologist: A wine scientist. Often referred to as a winemaker.
Viticulturist: A person who specializes in the science of the grapevines themselves. Can also be someone who manages a vineyard.