Leslie Lamport
loreprogrammingcloud
The 2013 Turing Award recipient for imposing order on distributed systems: logical clocks, distributed snapshots, Paxos, Byzantine fault tolerance, the safety and liveness distinction - and LaTeX.
His 1978 paper on time, clocks and the ordering of events is among the most cited in computing, and its point is that in a distributed system there is no global now - only causality, which you can order without a shared clock. Everything downstream depends on that: consensus, replication, and every database that must decide which write happened first. His own line describes the field better than any textbook: a distributed system is one in which the failure of a computer you did not know existed can render your own computer unusable.
Also known as: lamport, paxos, tla+