Robert Jacob "Jake" Arnold (born 3 January 1984 in Santa Rosa, California) is a decathlete from the United States. He represented the United States in the decathlon at the 2007 and 2009 World Championships ranking 13th and 24th respectively. He became the first athlete to win back-to-back NCAA decathlon titles in over twenty years after winning the event in both 2006 and 2007.
His personal best in the decathlon is 8253 points, while his indoor heptathlon best is 5909 points.
Arnold went to his home town Maria Carrillo High School, where he qualified to the 2002 CIF California State Meet in three events, the 110 meters hurdles, the 300 meters hurdles and the pole vault.
He came to prominence with a number victories during his college career at the University of Arizona. He placed fifth in the heptathlon at the 2006 NCAA Men's Indoor Track and Field Championship, earning All-American honours, and won the Pac-10 decathlon title in the outdoor season with a personal best of 7691 points. He improved upon this with a total of 7870 points en route to winning his first decathlon title at the NCAA Men's Outdoor Track and Field Championship. He capped off the season by taking third place in the decathlon at the 2006 USA Outdoor Track and Field Championships, scoring 7827 points to finish behind Ryan Harlan and Tom Pappas.