23 Massive Athletes You Don’t Want To Go Up Against

17. Ivo Karlovic — Tennis

There’s tall, and then there’s Ivo Karlovic tall. Measuring in at 6’11”, Karlovic is taller than the recommended height for umpire chairs in his sport. This tennis giant holds the record for most career aces, and his 144-mile-per-hour serve is the second highest recognized by the ATP.