Aspell gave Many Clouds a smooth ride around the 4 1/2-mile (6,400-meter) course and held off Saint Are to win by a length and three-quarters at odds of 25-1.
Twelve months after winning aboard Pineau De Re, Aspell celebrated becoming the first jockey in 61 years to win successive Nationals on different horses. Not bad for a jockey who quit the sport in 2007 after losing his passion for racing, only to return 18 months later saying he missed the thrill.
"If you look back now, it was a crazy decision," the 38-year-old Aspell said. "But it has given me new-found enthusiasm."
The winning time was 8 minutes, 56.80 seconds, short of the fastest ever time set by Mr Frisk in 1990 at 8 minutes, 47.8 seconds.
Owner Trevor Hemmings earned 561,300 pounds ($820,000) from the victory, his third in the world's most prized jumps race in just 10 years after Hedgehunter in 2005 and Ballabriggs in 2011. Only three other owners have three wins with different horses— and none in the past 100 years.
Hemmings is the owner of Preston North End, a third-tier English football club, and the former owner of a British holiday camp that made him his fortune. Many Clouds cost him 6,000 euros ($6,360) seven years ago — and has won him nearly 800,000 pounds since.
McCoy, Britain's most successful jumps jockey with 19 titles, finished fifth on pre-race favourite Shutthefrontdoor in his final Grand National before retirement, after being in contention for most of the race.
The Northern Irishman is due to end his illustrious career at Sandown on April 25, but would have quit on the spot if he'd have won the National for the second time. That would have been one of the most emotional story lines in British horse racing — and would have cost British bookmakers an estimated 50 million pounds ($73 million).
Many Clouds settled early and was never far from Shutthefrontdoor, the 6-1 favourite in McCoy's record-setting 20th and last ride around Aintree.
Coming to the final fence, Many Clouds had surged three lengths ahead of Saint Are as Shutthefrontdoor started to fade. Many Clouds still had enough left in him in the long finish to hold off Saint Are (25-1) to the post.
"I was very happy for a lot of the way," McCoy said. "I was following up behind Many Clouds, who I know is a dour stayer ... but going around the final bend I felt I was running on empty."
Nineteen of the 39 starters made it to the finish and there were no horse deaths for the third straight year. Renewed safety fears were raised by campaign groups after two horses died in both the 2011 and '12 editions.
Balthazar King, one of the favourites, had a heavy fall at the Canal Turn and received medical attention on the course, forcing the field to bypass the fence on the second circuit. The horse was transported to a local equine hospital for further assessment treatment.
Nina Carberry, the only female jockey in the race, finished 16th on First Lieutenant.
Many Clouds won the Hennessy Gold Cup in 2014 but had a disappointing race in the prestigious Cheltenham Gold Cup in March, finishing sixth. Trainer Oliver Sherwood had second thoughts about entering him for the Grand National but Hemmings thought otherwise.
"What do trainers know?" Sherwood said, with a chuckle. Sherwood hadn't had a horse finish the National in four previous attempts.
The last jockey to win successive Nationals on different horses was Bryan Marshall in 1953-54. Brian Fletcher was Red Rum's jockey when the National's most storied horse won back-to-back races in 1973-74.
Aspell joins the roll of honour, continuing his resurgence since returning to racing in 2009 after a spell out of the saddle following a heat-of-the-moment decision to retire.
"Last year, I was shell-shocked and I had to work hard," Aspell said. "This year, I had a smooth ride."