Merge sort emerged from John von Neumann’s early stored-program work as a disciplined way to turn sorting into smaller sorting problems plus a linear merge, establishing a pattern that remains fundamental to algorithm design.
Heapsort joined a compact tree-shaped data structure with an in-place sorting procedure. Williams introduced the core idea in 1964, and Floyd quickly supplied an efficient construction and implementation pattern close to the one still taught today.
Tony Hoare's Quicksort made partitioning the heart of sorting: rearrange data around a pivot, then solve two smaller sorting problems recursively in place.