The nine-year-old gelding will carry 11st 10lb in the race on Saturday 9 April.
Trained by Oliver Sherwood, Many Clouds carried 11st 9lb to win under Leighton Aspell last year. The last horse to have won twice in a row was Red Rum in 1973-1974.
Many Clouds, who is owned by Trevor Hemmings, is the 12/1 clear 2016 Grand National favourite with Betfred.
The famous race is worth £1m.
Five of the first six horses home in 2015 are among the 126 entries – runner-up Saint Are (Tom George, 10st 5lb, 33/1 with Betfred), fourth Alvarado (Fergal O’Brien, 10st 2lb, 40/1), fifth Shutthefrontdoor (Jonjo O’Neill, 10st 11lb, 25/1) and sixth Royale Knight (Dr Richard Newland, 10st 1lb, 50/1).
Andrew Tulloch of Aintree said: “The 169th renewal of the Grand National is all set to be one of the strongest ever Grand Nationals with no less than 83 of the 126 entries currently in the handicap, having been allotted 10 stone or more.
“It will be fascinating to see if Many Clouds can become the first back-to-back winner since Red Rum 42 years ago, particularly as he is in the unique position of being only set to carry a pound more than when successful in 2015.”
In addition to Many Clouds, there is another horse attempting to win a second Grand National in Pineau De Re (Dr Richard Newland, 10st 2lb, 50/1).
Other contenders with winning form over the Grand National fences include this season’s Becher Chase scorer Highland Lodge (James Moffatt, 10st 2lb, 50/1) and Triolo D’Alene (Nicky Henderson, 11st, 33/1) who collected the 2013 Crabbie’s Topham Chase.
There are 38 Irish-trained horses entered, including last’s season’s RSA Chase hero Don Poli (Willie Mullins, 11st 9lb, 25/1), Carlingford Lough (John Kiely, 11st 7lb, 25/1), who recently won the Grade One Irish Gold Cup for the second year in succession and Sir Des Champs (Willie Mullins, 10st 13lb, 40/1) who was runner-up in the 2013 Cheltenham Gold Cup.
Other contenders trained in Ireland include the 2015 Irish Grand National victor Thunder And Roses (Sandra Hughes, 10st 6lb, 50/1), 2014 Crabbie’s Grand National third Double Seven (Martin Brassil, 10st 1lb, 50/1) and Goonyella (Jim Dreaper, 10st 8lb, 25/1), who won last season’s Midlands Grand National at Uttoxeter and finished runner-up in Ayr’s Scottish Grand National. Ted Walsh has two contenders with dual Grade Two winner Foxrock (11st 3lb, 50/1) and Seabass (9st 12lb, 100/1), who was third in 2012.
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Champion trainer Paul Nicholls has more entries than any other trainer, with nine engaged. These are headed by seven-time Grade One victor Silviniaco Conti (11st 8lb, 25/1) and Just A Par (10st 6lb, 40/1), who triumphed in last season’s bet365 Gold Cup at Sandown Park.
There are two past winners of the Cheltenham Gold Cup engaged with the 2014 scorer Lord Windermere (Jim Culloty, 11st 1lb, 66/1) and the 2011 victor Long Run (Robert Waley-Cohen, 10st 8lb, 33/1).
Other contenders prominent in the market include Houblon Des Obeaux (Venetia Williams, 11st 5lb, 33/1), who bounced back to form with a Grade Two victory at Newbury, Kruzhlinin (Philip Hobbs, 10st 7lb, 33/1), who finished 10th in 2014 and recorded an eye-catching victory at Kempton Park last month and The Druids Nephew (Neil Mulholland, 11st, 25/1), who was leading the field when falling at Valentine’s on the second circuit last year.