The Gendo Pose, also known as the Ambassador's Pose, or Finger-Tenting is a media trope often associated with anime character Gendo Ikari of Neon Genesis Evangelion in which a character, usually villainous, poses with their fingers intertwined and resting over their mouth to look devious. The image has inspired numerous photoshop parodies and references in fan art where various characters strike the pose, starting around 2005.
It is unknown when finger-tenting first began. An early example can be seen in the 1976 anime series All-Star Combattler V (shown below).
On October 11th, 1995, Episode 2 of the anime series "Neon Genesis Evangelion" aired on Japanese television. In the episode, the character Gendo performs the Ambassador's Pose while discussing current events with the Human Instrumentality Committee (shown below).
It's unknown when exactly the term "Gendo pose" was coined, but started becoming popular online in 2005, when web users began making direct reference to the scene from Episode 2 in fanart and posts, particularly on sites like Deviant Art (examples from 2005, 2006 shown below, respectively).
The pose has resulted in numerous pieces of fanart referencing it. For example, on September 14th, 2014, Deviant Art user Kamixaqui posted a piece of art depicting a Medic from video game Team Fortress 2 doing the pose, garnering over 2,000 views in seven years (shown below).
Years later, the pose remains widely parodied both online and by other anime and manga series', such as in the 2015 anime Himouto! Umaru-chan, and in Attack on Titan, performed by Hanji (shown below, left and right).
A .PNG file of Gendo's arms and glasses, meant to be photoshopped over various images of people to give them the pose, has also seen considerable popularity on imageboards, resulting in a number of humorous variants (example shown below).