WPA is WiFi Protected Access - it's the most common method of encryption used to secure a wireless network. If you have a laptop or smartphone and you're trying to connect to a WiFi network, you'll usually need to enter a WPA key (or password) in order to connect to it.
In the live-action adaptations by Sir Peter Jackson, Sauron is portrayed by Benedict Cumberbatch in The Hobbit trilogy (who also portrays Smaug in the same trilogy) and was played by Sala Baker and voiced by Alan Howard in The Lord of the Rings trilogy.
Radagast appears in The Silmarillion where he played a part in helping Saruman, who was a member of the White Council, which was formed to stand against Sauron (although he was not a member of the Council himself).