Did you know that there weren't any Nobel Prizes EVER awarded for advances in theoretical General Relativity? Even Einstein himself got the prize ostensibly for the discovery of the photoelectric effect. Since then, the field was decidedly starved for prizes. In a related field of cosmology, there was one half the prize awarded for stellar evolution, one half for stellar nucleosynthesis, and a couple for CMB, but that only covers a tiny portion of the field.
I'd expect to have seen prizes awarded to:
- Hawking and Penrose
- Friedmann/Lemaitre/Robertson/Walker/Hubble or some subset thereof
- Gamow, the father of the Big Bang (and, incidentally, a student of Friedmann)
- Arnowitt, Deser & Misner