From seeing Roman marble copies of Greek bronze statues, it’s clear that Roman sculptors possessed an incredible amount of skill. But I’m not familiar with Roman originals, outside of portraits of Emperors and wealthy patrons. Even then, these are done in Greek motifs and poses.
I'm not big into sculpture, but one statue that I always love is the Augustus of Prima Porta. It is decorated beautifully, with the scenario in the middle representing the giving back of the standards by the Parthians. Anyway, you should see it for yourself, if you are not familiar. This is definitely a famous original.