Yousuf Karsh (1908–2002), Turkish-born, Armenian-Canadian photographer.
These images have been taken from the Yousuf Karsh collection at the Library and Archives of Canada, where they are marked as "copyright expired, no usage or reproduction restrictions". There has been some discussion surrounding the image of Albert Einstein, where someone claimed the image was copyrighted. The copyright office of the Library and Archives of Canada have confirmed that their labelling of these images was indeed correct and these images were in the public domain, stating that "according to the Copyright Act, any photos which are not created by a crown institution, are Public Domain if [...] created prior to January 1, 1949." See Image talk:Albert Einstein.jpg for more information.
The copyright status of these pictures in the US is unclear