You might not be familiar with Jan Tschichold's name, but the evidence of his work in typography is all around us. In 1928, heavily influenced by Bauhaus and Russian constructivism, Tschichold published The New Typography and laid out rules that, as Richard Hollis reports, are still the foundation of elegant design. Tschichold was only 26 at the time:
Those posters are objects of beauty, and you can see some examples of them as well as Tschichold's famous update of the Penguin paperback design in the gallery here. His work isn't flashy, and even a design nerd like myself has to look twice to spot the changes he made to the Penguins. He just made things look better. A lot better.