2018 and 2019 winner Clan Des Obeaux and current holder Frodon are among 10 confirmations for the Ladbrokes-sponsored event, which also has Cheltenham Gold Cup winner Minello Indo included on the racecard.
Clan Des Obeaux is the narrow favourite to wrestle back the crown on what will be his seasonal reappearance, while Frodon made a successful start to his campaign at Down Royal in October. Saint Calvados is a third runner for Nicholls.
Minella Indo will bid to provide Henry de Bromhead and Rachael Blackmore with another big-race triumph on British soil.
The eight-year-old can be expected to improve from his third-placed finish behind Frodon at Down Royal and plenty will fancy him to become the first Irish-trained winner since Kicking King in 2005.
It is 20 years since Willie Mullins saddled the popular Florida Pearl to claim King George glory and Ireland's perennial champion trainer this year looks set to launch a twin assault.
Asterion Forlonge appears the stable's number one hope, having looked set to play a major part in the John Durkan Memorial Punchestown Chase earlier in the month before unseating his rider three fences from home.
He is likely to be joined by Tornado Flyer, who finished fifth in the John Durkan.
Nicky Henderson is represented by Mister Fisher and Chantry House, with the latter a leading contender after readily accounting for his solitary rival on his seasonal debut at Sandown.
The Colin Tizzard-trained Lostintranslation has disappointed in the King George twice before, but connections will have taken heart from his return to form when winning at Ascot last month.
Jeremy Scott's stable star Dashel Drasher completes the potential line-up.