Demopan is a user-generated character based on the demolition expert "Demoman" from the first-person shooter game Team Fortress 2. Donning an eclectic assortment of items like shutter shades and a frying pan, the character was designed to parody the insane volume of custom accessories and weapons that have been added to the game since its inception.
On December 17, 2010, Reddit user ichbinpwnzilla posted a TF2 Deathcam screenshot titled "The New Face of TF2" to the subreddit /r/tf2 (shown below). The screenshot features a player named "STOUT SHAKO FOR 2 REFINED" as the Demoman character wielding a Chargin' Targe and a Frying Pan while wearing shutter shades and a Bounty Hat. The latter three items were released within three months before ichbinpwnzilla's post, while the Chargin' Targe was released a year before. The Imgur post for the image reads "From America's #1 hat-themed war simulator," indicating that it was intended to highlight how much Team Fortress 2 had changed since its release in 2007.
On December 18, 2010, on the Steam Powered User Forums, user pikagrue posted the image in a thread titled, "The New Face of TF2". The thread title was later changed to "The New Face of TF2, OR THE DEMOPAN THREAD" when the OP realized that the thread was turning into a copy & paste meme thread. It was on this thread that caused photoshops of Demoman to become popular.
The meme saw further spread on YouTube. On December 31, 2010, YouTuber SpawnThemAll posted a Meet The X video titled "Meet The Demopan" that gained over 500,000 views in eleven years (shown below, left). On January 5, 2011, YouTuber TheDemopan posted a YouTube Poop Music Video featuring the Demoman that received over 1.8 million views in the same period (shown below, right).
In 2011, the Team Fortress Wiki made an article about Demopan a trending topic as part of an April Fools' Day joke.
Steam user TenthDog responded by creating the first template of the character, making Demopan an exploitable: