Adam John Holland (born 1987) is an English distance runner who has won over 300 marathons and ultra-marathons. In 2010, he became the youngest person to complete 100 marathons in Europe, doing so at the age of 23. Six years later, he set a new record for the fastest cumulative time to complete 10 marathons in 10 days, doing so in over an hour quicker than the previous record. He later beat his own record in 2017, setting a time of 27 hours, 38 minutes and 36 seconds, almost another hour quicker again. He has won more marathons and ultra-marathons than any other runner in Great Britain, and the fourth most of anyone in the world.