SCP-173 (found 4chan post; 2007)
The original SCP-173 post is a 2007 4chan post that lead to the creation of the SCP Foundation, a popular horror writing website. The post was made on June 22, 2007, and deleted a few days later. It was lost for over a decade, before being rediscovered in an archive of old 4chan posts by dasMaymay. The original post, as well as the entire thread, can be viewed here.
SCP-173 was originally a creepypasta posted to the /x/ (paranormal) board of 4chan in 2007. The post described the procedures needed to safely contain a paranormal statue that could move and attack people when not looked at. This sparked a popular community of related horror writing in the same format, known as the SCP Foundation.
The original SCP-173 post was made on June 22, 2007. 4chan does not save old posts, so any thread that is not externally archived will be automatically deleted. One member of the SCP Foundation Wikidot website estimated that the original post only survived for a few days before being deleted. The text and image used in the post were saved, and can currently be viewed on the SCP Foundation Wikidot website. However, the original post was lost. Since 2007, many members of the SCP Foundation community and fandom have tried to find the original post or information about it. Several archives such as the Yotsuba Society, the Chanarchive, and many /x/ thread dumps stored on the Internet Archive were searched for the post without success.
On October 8, 2018, Jason Scott of the Internet Archive posted an archive of about 10 million 4chan posts from 2006 to 2008 onto the Internet Archive. On that day, dasMaymay searched through the archive, found the original thread and posted it to the SCP Foundation subreddit.
Details Known About the Original Post Before Its Rediscovery
The oldest surviving text of SCP-173 was posted on June 22, 2007, at 12:33 PM Greenwich Mean Time (8:33 AM Eastern Standard Time). The original post was thus made on or before June 22, 2007.
The author of 173 posted under the username “The USS Walrus”. He initially planned to make a new SCP post every week, but lost internet access for a week and a half and forgot about the SCP Foundation until over a year later.  In other words, 'The USS Walrus" did not re-post the text of SCP-173. If a 2007 4chan post containing both the text of SCP-173 and the author name "The USS Walrus" is discovered, then the post will almost certainly be the original post.
SCP-173 was posted around the same time period as “Blink”, a Doctor Who episode which aired on June 9, 2007, and introduced the Weeping Angels. The Weeping Angels are sentient statutes that attack when not looked at. Members of the SCP Foundation claim that the SCP-173 post was made weeks or months before “Blink” aired. However, no physical proof exists to support these claims.  The publication date of SCP-173 was in controversy for years, but the original post shows that it was made several weeks after Blink first aired.
The text of SCp-173 may have changed over time. The text of the 2008 4chan post, as well as many 2007- early 2008 forum posts, varies from the current text of SCP-173. The original post confirms that the text went through several alterations.
- http://www.scp-wiki.net/forum/t-228926/site-history#post-731676 Archived version
- https://www.reddit.com/r/SCP/comments/8gpt4k/does_scp173_actually_predate_the_weeping_angels/dye9zgn Archived version
- https://web.archive.org/web/20180111021822/http://z6.invisionfree.com/DeadlandsFreeRunners/ar/t68.htm, live version with NSFL images 
- http://www.scp-wiki.net/forum/t-77831/wow-i-never-expected-this#post-230929 Archived version
- https://www.reddit.com/r/SCP/comments/8gpt4k/does_scp173_actually_predate_the_weeping_angels/ Archived version.
- See: 12 (link slightly NSFW)3