With 2015 approaching its end and welcome 2016, fans have enjoyed various viral videos that surfaced online.

Animal videos like cats and dogs are also constant achievers when it comes to being viral. A case in point is the video of Otto, the skateboarding bulldog in Lima, Peru. On his skateboard, Otto managed to travel the longest human tunnel, which was comprised of 30 people.

With his feat, Otto now holds the Guiness World record for the longest human tunnel travelled through by a dog skateboarder. Posted by Guiness World Records on Nov. 12, Otto's video got more than 1.2 million views on YouTube.

Among the viral videos this 2015 is the top pop music hits medley posted by Us The Duo. With just a piano accompaniment, the duo were able to deliver several chunks of song parts in their clip, which included "Hello" by Adele, "Thinking Out Loud" by Ed Sheeran, "Drag Me Down" by One Direction, and "Bad Blood" by Taylor Swift featuring Kendrick Lamar, among others.

Running for three minutes and 26 seconds, Us The Duo's clip got more than 2.4 million views on YouTube.

Another viral video featured a girl named Heaven King, who is undeniably known for her appearance in The Ellen Show. In the video, King showed off her groovy dance movies, with the musical accompaniment of "Watch Me (Whip/Nae Nae)" by Silento.

It is assumed that one unique element that separates the clip from other viral videos is the presence of a five-year old girl, who has made an appeal to people in different parts of the world with her amazing talent.

Uploaded by Tianne King on Apr. 22, "Heavens" viral clip made more than 119 million views.

Since it is only half-way to the end of December, more 2015 viral videos will be recalled as the year ends and more viral videos are set to come in 2016.