The Federation Starship Main Computer
Since the original series debut in September of 1966, Star Trek has been filled with numerous examples of intelligent robots and computers. But only one of them has been in every single incarnation of the iconic Sci-Fi franchise's TV and Film versions -- the shipboard computer.
Only known as "The Computer", or "Main Computer", and voiced by actress Majel Barrett (who married Star Trek creator Gene Roddenberry and starred also as Nurse Chapel and recurring character Lwaxana Troi) the crew members frequently interacted with it in order to solve complex problems. While it had no distinct personality and was not known to volunteer information or instigate conversation, it was clearly capable of advanced cognitive thinking.