The Storyteller was the only withdrawal as the final field of 40 horses – headed by Cloth Cap – was named for the Grand National on Saturday.
It means Blaklion is the last horse to be guaranteed a run in the big race at Aintree.
Some Neck and Welsh Grand National winner Secret Reprieve are the top reserves.
Patrick Mullins will ride leading contender Burrows Saint for his trainer father Willie Mullins.
Stable jockey Paul Townend will miss the ride after suffering a foot injury.
A reserve can make the line-up if any contenders are pulled out before 13:00 BST on Friday.
Cloth Cap, trained by Jonjo O’Neill, is the 4-1 favourite to give owner Trevor Hemmings a record fourth win in his green, yellow and white colours.
Mullins is one of four amateur jockeys to be booked for rides in the race – with Jamie Codd on Milan Native, Derek O’Connor riding OK Corral and Sam Waley-Cohen aboard Jett.
They will be bidding to be the first amateur rider to triumph since Marcus Armytage on Mr Frisk in 1990 and are permitted to ride after the latest easing of lockdown restrictions, having been barred from competing at last month’s Cheltenham Festival.
One contender who looks sure to be popular is Minella Times, the mount of Rachael Blackmore – who made history at Cheltenham by becoming the first woman to be leading jockey at the meeting.
Bryony Frost is on Yala Enki and Tabitha Worsley rides Sub Lieutenant in the hunt to be the first female jockey to win the Grand National.
Last year’s meeting was called off because of the Covid-19 pandemic, while this year’s contest will be held without spectators.
Police are stepping up patrols around the meeting, with residents close to the Merseyside track warned not to gather in groups larger than six in their gardens during the races.