My votes for relatively modern stuff: Ed Witten: Unification of various forms of string theory.

Category theory and the work building programming langauges on top of that.

If the whole thing pans out: Langlands Program (unifying most of mathematics).

Wofram Language and the math capability is pretty amazing for such a small team.

Anything that CERN touches, from the web to various quantum theories.

Genetic mapping and science.

The Lambda CDM model, and all the work that goes into constraining their predictions with limited data is pretty amazing.

Some of the things cryptanalysts and hackers do is pretty remarkable. Side channel attacks like Row hammer attacks (not strictly crypto), EM analysis, etc..., and things like hash collisions and Differential cryptanalysis.

Modern materials science is chock full of amazing intellectual achievements.

"Winning ways for your mathematical plays" as a book on game theory is a remarkable achievement by itself.