Whenever a new SF author tries his or her hand at writing an epic Space Opera series, they quickly begin to realize that its all pretty much been done before. You have to be very outside the box not to include galaxy spanning civilizations, huge starship fleets, dashing heroes and evil villains. Even when it comes to the technology of the genre; ray guns, hyper-space drives and huge, planet crushing weapons, you can be sure that someone has already done it all before you.
Usually, that someone is named EE “Doc” Smith, the grandfather of the modern Space Opera. His Triplanetary novel and Lensman stories contain all the staples of the genre and they were written in the 1930’s through the 1950’s. Many tropes of the genre were done by Smith before anyone else. If you want to know where Space Opera was born, read Smith. Like students of history, you have to know what has come before, before you can show where it will go in the future. I have not read the entire Lensman series yet, but I am making my way through it.
The other pillar of the genre is of course Isaac Asimov and his seminal Foundation series. Both of these Space Operas should be required reading before you wade too far into the deep, dark waters of creating your own Space Opera series. I say this having read neither of these authors extensively before starting my own Space Opera. I don’t completely regret it, but I wish that I had a more than passing familiarity with both before I had written Starstrikers. My only defense is that I did read over 200 SF novels in my teens and much of that genre goo was absorbed into my pores pretty good, by the time I started creating my universe.
Now much later in my life, as I read Smith and Asimov, and others that have gone before me, I start to understand where these concepts and constructs all came from originally. Sometimes I have to admit that I’m not as clever as I thought I was. Which is amusing. The creators of later Space Operas like Star Wars and Star Trek have already drunk from the well of Asimov and Smith. Some of them have taken quite a bit from the Masters, but none of them have come close to the grandeur of those original stories. Do yourself a favor as a genre writer and read the classics. You will be surprised and enlightened by what your find.