Even if you don’t want Doctor Who, here’s an interesting look at how something like this evolves over time. The first episodes aired in 1963 and new episodes and new Doctors kept coming off and on until now! There should be about… 10 different intro themes, but I’m not sure. Frankly, I lose count while I watch! :D
But see if you can guess the eras that these different intros aired! I was definitely able to pick out the 80s and 90s, but each other one seems to have its own era signature, too.