The ad features clips of surprising friendships between animals of different species, like an orangutan and dog playfully rolling in the grass. Given the internet's fondness for animal videos, it has unsurprisingly attracted 6.4 million shares online since it debuted in February.
The spot not only comes in as the most shared of the year, but the most shared of all-time, according to Unruly. It surpases the previous leader, Activia's "La La La," which has attracted about 6 million shares since its launch in 2014.
And it was far and away the most shared ad of the year, with No. 2, Walt Disney's "Disney Characters Surprise Shoppers," shared 3.9 million times.
Unruly based its ranking on the number of shares, not the number of views, that ads attracted across Twitter, Facebook and other social platforms this year through Nov. 16. The ranking only includes ads that debuted in 2015 and excludes trailers for movies or TV shows.
Animal-themed commercials dominated the top 20, with an ad created by Buzzfeed Video for Purina pet food coming in at No. 3. "Man Found His Soulmate in a Puppy and It's Adorable" has been shared over 3 million times.
Budweiser's Super Bowl commercial, "Lost Dog," ranked No. 5 with 2.8 million shares. Despite everyone's love for puppies, interestingly enough, Anheuser-Busch InBev told Ad Age this week that they won't be returning to Bud's Super Bowl ads because they don't sell beer.
Kleenex's "Unlikely Best Friends" was 10th with 2 million shares.
Public service announcement and ad campaigns supporting good causes were also popular.
The Ad Council's "Love Has No Labels," which promoted diversity and inclusion is No. 6, with 2.7 million shares. It is one of eight campaigns that support good causes that place in the top 20.
Other examples include a Microsoft spot starring actor Robert Downey Jr. giving a young boy a prosthetic arm; an anti-domestic violence PSA from Italian newspaper Fanpage.it; and a "Game of Thrones" and Coldplay partnership for Red Nose Day, which helps lift children out of poverty; and John Levis' Christmas spot.
Adidas had the most commercials of any one brand make it onto the top 20, with three spots appearing on the list.
While 2015 was a year of feel-good ads and spots that promote doing good, Unruly co-CEO and co-founder Sarah Wood predicted that next year advertisers will move away from warmth and happiness to exhilaration. With movies like "Batman vs. Superman" and "Pride and Prejudice and Zombies" being released in 2016, Ms. Wood said we can expect marketers to follow Hollywood with similar themes.
"Going into a quadrennial year of Olympics, European Championships and Presidential elections, the competition for consumer attention will be fierce and consumers will be looking for superhero brands to exhilarate and entertain them in 2016," she said in a statement.
Ads for Samsung, Pandora and MetLife, also make it into the top 20.
Chart by Chen Wu