Websites blocking Tor or making it difficult for users to connect to

In this ticket we are going to document instances where websites, especially the ones in top 500 in terms of traffic, are deliberately blocking or making it difficult for users to access their website on Tor. Please feel free to add to this ticket with some proof and/or a little description of any such incident. More information on this can be found on our wiki.
General advice that we give folks when running into this issue can be found in our Support Portal.