Stefan Kanchev (1915-2001) isn’t necessarily the guy you learn about in an art or design history class but his works and achievements are definitely worth much praise. He has designed 650 stamps, over 1000 trademarks and symbols, posters, book covers, and the list goes on. The Stefan Kanchev project team have developed a wonderful collection of his artifacts. Although the project is ongoing you can find most of his work there.
Via designboom