Nobel watchers also speculated that negotiators of an accord over Iran's nuclear programme could be in the running after a surprise award last year to a coalition of Tunisian democracy campaigners, the National Dialogue Quartet.
"2016 may finally be Edward Snowden's year ... His leaks are now having a positive effect," Kristian Berg Harpviken, head of the Peace Research Institute, Oslo, told Reuters, putting him top of his list of candidates.
Harpviken said many nations were now reforming laws to restrict intelligence gathering, helping human rights, in the wake of Snowden's leaks in 2013 of details of the U.S. government's surveillance programmes.
Washington has filed espionage charges against Snowden, who has been granted asylum in Russia. An award of the $930,000 prize to Snowden, by a Nobel committee in NATO member Norway, would be a huge snub for President Barack Obama, the 2009 Nobel laureate.
Asle Sveen, an historian and expert on the prize, said he reckoned the "obvious choice" for 2016 would be to honour Colombia's government and FARC rebel group - if they succeed in peace talks launched in 2012 to end five decades of war.
He noted Norway's government had been involved in organising peace talks, perhaps swaying the five-member Norwegian Nobel committee which is appointed by parliament. February 1 is the annual deadline for nominations.
Harpviken placed Colombian peace negotiators third on his list, behind US Energy Secretary Ernest Moniz and Ali Akbar Salehi, head of Iran's Atomic Energy Organization, for their role in negotiating a deal last year to limit Iran's nuclear programme.
That accord led to a lifting of sanctions by major powers on Tehran last month.
Other candidates include Greek islanders who have helped Syrian and other refugees - a campaign by grassroots group Avaaz has collected 635,000 online signatures for a prize to islanders who "have opened their homes and hearts".
But it could be difficult to identify Greek winners under the plans set out by Alfred Nobel, the Swedish founder of the prize. The award can be split up to three ways, to individuals or organisations.
Sveen said other candidates may include Russian human rights groups such as Memorial, nominated by Norwegian Prime Minister Erna Solberg before she took office in 2013.
"Huge numbers of nominations are still coming in," said Olav Njoelstad, Director of the Norwegian Nobel Institute. The committee will have its first meeting on February 29 and announce the winner in October.
Thousands of people, including members of all national parliaments, former laureates and university rectors, can make nominations. Last year there were 273 nominees.
Harpviken said a US nominator, whom he did not identify, had proposed US Republican presidential front-runner Donald Trump for his "vigorous peace through strength ideology". He did not list Trump among those with a chance of winning.