Jonathan Bruce Postel (/pəˈstɛl/; August 6, 1943 – October 16, 1998) was an American computer scientist who made many significant contributions to the development of the Internet, particularly with respect to standards. He is known principally for being the Editor of the Request for Comment (RFC) document series, for Simple Mail Transfer Protocol (SMTP), and for administering the Internet Assigned Numbers Authority (IANA) until his death.

During his lifetime he was referred to as the "god of the Internet" for his comprehensive influence; Postel himself noted that this "compliment" came with a barb, the suggestion that he should be replaced by a "professional," and responded with typical self-effacing matter-of-factness: "Of course, there isn’t any 'God of the Internet.' The Internet works because a lot of people cooperate to do things together."

Postel attended Van Nuys High School, and then UCLA where he earned his B.S. (1966) as well as his M.S. (1968) in Engineering. There he completed his Ph.D. in computer science in 1974, with Dave Farber as his thesis advisor.

Postel started work at UCLA on 23 December 1969 as a Postgraduate Research Engineer (I) where he was involved in early work on the ARPANET. He was involved in the development of the Internet domain system and, at his instigation, Vint Cerf and Bob Kahn developed a second set of protocols for handling data between networks, which is now known as Internet protocol suite. Together with Cerf and Steve Crocker, Postel worked on implementing most of the ARPANET protocols. Cerf would later become one of the principal designers of the TCP/IP standard, which works because of the sentence known as Postel's Law.

Postel worked with ARPANET until 24 August 1973 when he left to join MITRE Corporation. He assisted with Network Information Center, which was being set up at SRI by Elizabeth Feinler. In March 1977, he joined the Information Sciences Institute at the University of Southern California as a research scientist.

Postel was the RFC Editor from 1969 until his death, and wrote and edited many important RFCs, including RFC 791, RFC 792 and RFC 793, which define the basic protocols of the Internet protocol suite, and RFC 2223, Instructions to RFC Authors. Between 1982 and 1984 Postel co-authored the RFCs which became the foundation of today's DNS (RFC 819, RFC 881, RFC 882 and RFC 920) which were joined in 1995 by RFC 1591 which he also co-wrote. In total, he wrote or co-authored more than 20 RFCs.

Postel served on the Internet Architecture Board and its predecessors for many years. He was the Director of the names and number assignment clearinghouse, the Internet Assigned Numbers Authority (IANA), from its inception. He was the first member of the Internet Society, and was on its Board of Trustees. He was the original and long-time .us Top-Level Domain administrator. He also managed the Los Nettos Network.

All of the above were part-time activities he assumed in conjunction with his primary position as Director of the Computer Networks Division, Division 7, of the Information Sciences Institute at the University of Southern California.