The good old Breyer Variation of the Ruy Lopez remains popular to this day. At one point it was one of Magnus Carlsen's favorite defenses.
1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1b5  3... a7a6  4. b5a4  4... g8f6  5. e1g1  5... f8e7  6. f1e1  6... b7b5  7. a4b3  7... d7d6  8. c2c3  8... e8g8  9. h2h3 