Two years ago former professional rugby player Lee Audis was unable to walk after suffering serious brain injuries in a car crash.
Lee, 25, of Wicks Drive, Chippenham, who used to play for Doncaster Knights, spent about eight months in a wheelchair after breaking his skull in November 2011.
But on Sunday he completed the 13.1-mile course on foot and managed to jog for three-quarters of the way.
He crossed the line just after the four hour mark and was accompanied the whole way by the three therapists who looked afer him during brain injury rehabilitation at Frenchay Hospital, near Bristol.
His dad, Toni, also ran, finishing his first half marathon in 3 hours 12.
Together they have raised more than £2,000 for the rehab centre at Frenchay.
Postman Mr Audis, 53, said: “Lee had to have an operation on his achilles and couldn’t walk for months, so it was quite emotional to see him come so far in just two years.
"He was determined to finish it and it was brilliant when he came over that finish line.”