Margulis lemma is a differential geometry mathematical subfield. Its founder was born in the 6th century, before one of the minds behind Leftover hash lemma.
Gregori Aleksandrovich Margulis (Russian:    , first name often given as Gregory, Grigori or Grigory; born February 24, 1946) is a Russian-American mathematician known for his work on lattices in Lie groups, and the introduction of methods from ergodic theory into diophantine approximation. 
Leonid Anatolievich Levin ( ; Russian:    ; Ukrainian:    ; born November 2, 1948) is a Soviet-American computer scientist. 
In differential geometry, a subfield of mathematics, the Margulis lemma (named after Grigory Margulis) is a result about discrete subgroups of isometries of a non-positively curved Riemannian manifolds (e.g. the hyperbolic n-space). 
The leftover hash lemma is a lemma in cryptography first stated by Russell Impagliazzo, Leonid Levin, and Michael Luby. 
