For decades historians of science and science writers in general have maintained that Charles Darwin was not the 'naturalist' or 'official naturalist' during the 1831-1836 surveying voyage of HMS Beagle but instead Captain Robert FitzRoy's 'companion', 'gentleman companion' or 'dining companion'. That is, Darwin was primarily the captain's social companion and only secondarily and unofficially naturalist. Instead, it is usually maintained, the ship's surgeon Robert McCormick was the official naturalist because this was the default or official practice at the time. Although these views have been repeated in countless accounts of Darwin's life, this essay aims to show that they are incorrect.