Super Mario Bros. 3 - The Ending
At the end of every world, the King of that country is transformed back to their human form and thanks you with a letter from Princess Toadstool and an item. When you defeat Bowser in World 8, the princess says "Thank you for saving me, but our princess is in another castle" (causing many a player an unnecessary heart attack after a day-long play session). She then says "Just Kidding. Thank you for playing. Goodbye." - The ending then features a shot of all the worlds the player has beaten to get to the end - you can view these images at our SMB3 Worlds & Maps section.
Super Mario Bros. 3 Ending video (NES VERSION)
Super Mario Bros. 3 Ending video (SNES VERSION - ALLSTARS)