Dennis Lappin is a Firefighter who first competed in Denver in American Ninja Warrior 6, he winded up suffering an injury on the second obstacle, the Cat Grab, While jumping to the first wall, his right leg hit the wall very hard, resulting a ruptured Achilles, and needed six months to recovery.
Dennis returned to compete in Kansas City in American Ninja Warrior 7, he became the first competitor to finish the qualifying course, he placed 29th and moved on to the city finals, in the city finals, Dennis failed the Body Prop but placed 15th and advanced to the national finals for the first time. His run on Stage 1 was cut but it was revealed that he failed the very first obstacle, Piston Road.
Dennis returned to compete in Kansas City again in American Ninja Warrior 9. In Qualifying his run was digested but it was shown that he finished the course, placing 10th, his run was digested again in the city finals, but it was shown that he failed the third obstacle, the Broken Pipes.