World number one Djokovic is the defending champion and chasing a fifth title at the All England Club, AFP reported.
Federer, promoted to second seed, can win a ninth crown while two-time champion Nadal is seeking to complete a rare back-to-back Roland Garros-Wimbledon double.
Twelve months ago, Djokovic arrived at Wimbledon with his career threatening to spiral into decline.
Unable to shake off the effects of right elbow surgery, the Serb was ranked at 21, his lowest position for over a decade.
But two weeks later, Djokovic had captured the 2018 title to add to his 2011, 2014 and 2015 wins, becoming the lowest-seeded player to take the Wimbledon trophy since Andre Agassi in 1992.
Since then, he has been rejuvenated, going on to claim a third US Open and seventh Australian Open title.
The only blip was a rain-hit semifinal exit to Dominic Thiem at Roland Garros, a loss which ended his attempt to become just the second man to hold all four Slams at the same time twice.
"Coming off from the surgery, being unable to have consistency with results, this was a huge springboard for me, the win at Wimbledon last year," said Djokovic, who will take a 10-2 career record over Philipp Kohlschreiber into their first-round clash on Monday.
Federer, chasing a 21st major, first played Wimbledon in 1999.
Pushing 38, he would be the oldest ever Grand Slam champion if he were to lift a ninth title.
The Swiss star is also just five wins from becoming the first man to register 100 victories at the same Slam.
'Better because of each other'
But Federer was quick to praise the influence of Djokovic and Nadal – between them, the trio have won 53 of the last 64 Slams.
"I think we definitely became better because of one another," he said.
Federer starts on Tuesday against South Africa's Lloyd Harris, who is making his Wimbledon debut.
Nadal, meanwhile, arrives in London on the back of a 12th Roland Garros title.
His 18th career major also meant he moved within two Slams of Federer's all-time mark for the first time.
The Spaniard, ranked two but – much to his irritation – seeded three was champion in 2008 and 2010.
He is now trying to join Bjorn Borg by achieving the Roland Garros-Wimbledon double for the third time.
Nadal was desperately close to a third title in 2018.
Having failed to get past the last-eight since 2011, the Spaniard was only defeated in an epic semifinal by Djokovic, 10-8 in the final set.
"I won here in 2010 after a very, very tough first couple of rounds. Sometimes that helps, especially in this event, that you arrive here without playing much on this surface," said Nadal, who starts his campaign against Japan's world number 258 Yuichi Sugita.
After that looms a possible titanic clash with Nick Kyrgios, who shocked him in 2014, in the second round.
It's been 17 years since anybody not named Djokovic, Federer, Nadal or Andy Murray captured the Wimbledon title.
That long-distant honor went to Lleyton Hewitt in 2002.
The problem for the chasing pack in 2019 is their record at the tournament as well as various frailties in body and spirit.
Thiem, Alexander Zverev and Stefanos Tsitsipas, who occupy the next three spots in the world rankings, have yet to get past the last 16 on Wimbledon's grass.
Kei Nishikori, the world number seven, was a quarterfinalist in 2018 while eighth-ranked Kevin Anderson, seeded fourth this year, was runner-up 12 months ago.
Anderson saved a match point to beat Federer in the quarterfinals.
His challenge to Djokovic in the final, however, was compromised by playing a six-hour 36-minute semifinal to beat John Isner.
It was the second longest match in the history of Wimbledon and decided by a 26-24 final set.
There will be no repeat of such lung-busting epics this year as Wimbledon has introduced a final set tiebreaker – at 12-12 – for the first time.