Two of my favorites are [the photo of Churchill,Roosevelt and Stalin taken at the Yalta conference](https://upload.wikimedia.org/wikipedia/commons/0/05/Yalta_Conference_%28Churchill%2C_Roosevelt%2C_Stalin%29_%28B%26W%29.jpg) and [the first selfie in space taken by Buzz Aldrin](https://upload.wikimedia.org/wikipedia/commons/thumb/e/e3/Buzz_Aldrin_self-photograph_during_Gemini_12_EVA_%28S66-62926%29.jpg/800px-Buzz_Aldrin_self-photograph_during_Gemini_12_EVA_%28S66-62926%29.jpg).