Aristotle Onassis was a leading figure in creating the new global tanker business in the second half of the twentieth century. This article examines the first thirty years of his career, before he became renowned worldwide, setting his business in the context of global shipping developments. Onassis is the most famous of the shipping tycoons that transformed maritime business in the post–World War II transitional period. He is among those “new men”—Greek, Norwegian, Danish, American, Japanese, or Hong Kong shipowners—who replaced the old order of the traditional British Empire shipowners. These new pioneers established the global shipping business in the era of American dominance.