Just trying to compile a list of major crossovers or somewhat moderate crossovers spanning the last twenty years. I don't know if DC did major event pre-crisis. I might be wrong, feel free to answer that.
-Crisis on Infinite Earth
-The Last Laugh
I know there is ton more.
Now more specific character crossovers.
-Knightfall, Knightquest, Prodigal
-No Man's Land
-Bruce Wayne: Murderer, Fugitive
-Death of Superman
-Funeral for a Friend
-Return of Superman
Far Far from complete, please add what I'm missing. If you have any opinion on them, feel free to express them.