Kepler is a modern serif font by Adobe type designer Robert Slimbach. Here are some fun facts about Kepler. 1. It’s named after Johannes Kepler, a German astronomer, astrologer, mathematician and philosopher. 2. It’s a contemporary take on the classic modern 18th century typefaces. 3. It features 4 optical size variations that have been optimized for use at specific point sizes. 4. It’s elegant and refined, so it’s very popular with printers and typesetters.