Unknown Sender is an internet television series created in the United States, which debuted in August 2008 on Strike.TV, a website created by Hollywood writers during the 2007–2008 Writers Guild of America strike; the series was later uploaded to YouTube. Like the other Strike.TV offerings which were sanctioned by the writers' sister union, the Screen Actors Guild, Unknown Sender was able to attract major talent to its cast, all of whom agreed to donate profits to the Hollywood charity, Actors' Fund. Among the actors in the series are Timothy Dalton, Joanne Whalley, Mindy Sterling (Austin Powers' "Frau Farbissina"), comedian Jay Davis (Dane Cook's Tourgasm), and Stan Freberg.

Behind the camera, noteworthy figures include Academy Award nominee Marilyn Vance and pioneer web filmmaker Kevin Rubio (Troops) among the producers; as well as Lost Director of Photography Edward J. Pei, film composer Adam Cohen (The Incredibles); and Special Effects Supervisor Shant Jordan (Hellboy II).