Quantum Leap was a science fiction TV series that first aired in the US in 1989, so I guess it only just qualifies as a subject for this site, but I feel it deserves a space here as I have good memories of watching it.
Scott Bakula played Dr. Sam Beckett, a scientist who in the year 1999 invented the Quantum Leap accelerator, a device that allowed time travel within the lifetime of the person travelling. Faced with having his funding cut Sam tests out the machine by using it himself, and so begins his travels through time.
Trouble is, something went a little wrong (or caca as the original introduction to the programme put it) and whilst Sam does indeed travel through time, he does so by having his consciousness jump into the bodies of people from the past.
Seemingly stuck, and initially not knowing where he is due to his “swiss cheesed” memory, he soon comes to rely on his erstwhile assistant Al Calavicci (played by Dean Stockwell). Al is broadcast back through time in the form of a hologram, and tries to help Sam out in whatever predicament he finds himself in.