Viewstamped Replication independently developed a primary-backup protocol with quorums and view changes, providing an early path to replicated state machines alongside the better-known Paxos lineage.
Erlang combined lightweight isolated processes, asynchronous messages and supervisory recovery into a programming model designed for long-lived telecom systems.
Research by Marshall Pease, Robert Shostak, Leslie Lamport, and the SIFT team exposed a hard boundary in distributed agreement: a faulty participant may send different lies to different peers, so redundancy alone is not enough unless the protocol accounts for adversarially inconsistent behavior.