Like most people, I first saw Christopher Reeve in Superman. My grandmother remembered him playing a bigamist in Love of Life back in the mid-1970s.
What made Christopher Reeve's version of Superman definitive was the delineation between his Superman and Clark Kent. Unlike some others who've taken on the role, his Superman was noble but not pompous--Reeve essentially let the uniform do the acting. Clark was a bumbling/stumbler with a different voice and mannerisms. Want to see a great bit of acting? Watch the scene in the first movie in Lois' apartment. Just after her ride with Superman, Clark appears to take Lois on a date. Lois leaves the room for a moment, Reeve takes off his glasses, grows about three inches in height, and BECOMES Superman. Reeve's voice lowers and he says "Lois, there's something I have to tell you, I'm really...". Then Lois appears, the glasses go back on, his height drops, and his voice rises about an octave, suddenly, he's Clark again.
Christopher Reeve was in a number of other movies which I encourage you to see: The Bostonians, the Remains of the Day, Somewhere in Time are but a few.
He was also a talented pianist. I remember an interview with Dana Reeve where she said she missed hearing him play even more than seeing him walk.
He suffered tragedy in 1995. Like Franklin Roosevelt, he used his misfortune to do a lot of good for many people. That's an example we can all try to emulate.
Rest in Peace.