The one that surprised me is Hooters. They were in Vienna, Budapest, and Prague just to name a couple places.
There is a KFC in Venice. There are several Taco Bell in Barcelona including one across the street from La Sagrada Familia. You can see a Burger King and a Subway "sandwich" shop from the Eiffel tower.
My travels in Europe surprised the hell out of me. Virtually every metro area is full of American trash food chains. The one cool thing is they sometimes have local variations on food. I ate at a KFC in Prague out of morbid curiosity and they had an interesting take on the spicy chicken sandwich.