This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages) This article may need to be rewritten to comply with Wikipedia's quality standards. You can help. The talk page may contain suggestions. (March 2019) This article contains wording that promotes the subject in a subjective manner without imparting real information. Please remove or replace such wording and instead of making proclamations about a subject's importance, use facts and attribution to demonstrate that importance. (March 2019) (Learn how and when to remove this template message) This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. Please help to improve this article by introducing more precise citations. (March 2020) (Learn how and when to remove this template message) (Learn how and when to remove this template message)

Michael J. (Mike) Karels is an American Software Engineer and one of the key people in history of BSD UNIX.

A graduate of University of Notre Dame with a Bachelor of Science in Microbiology. Mike went on to University of California, Berkeley for his advanced degree in Microbiology. Mike had access to the department's computer and since the administrator of that PDP-11 did not have enough time, Mike started helping him and then making changes to the system. Mike started his contribution to Unix with the 2.9BSD release, distributed for the PDP-11. When Mike saw a job posting with the Computer Systems Research Group in the BSD project, he decided to jump in. In 1982, Mike took over Bill Joy's responsibilities when Mr. Joy left CSRG, and was the system architect for 4.3BSD, the most important BSD release and the base of the development for a number of commercial Unix flavors available today, including Solaris. This release was introduced to the world in deep detail through the all-time famous book, The Design and Implementation of the 4.3BSD UNIX Operating System, with black cover and smiling beastie. Mike was a CSRG principal programmer for 8 years.

Mike worked closely with Van Jacobson on a number of widely accepted algorithms in TCP implementation. Including the Jacobson/Karels algorithm TCP slow start and the routing radix tree are probably the most famous ones. Mike spends little time taking credit for this work, and on the other hand, uses every opportunity to mention the names of people who had in one way or other some role or contribution to the TCP/IP implementation in Unix.

In 1993, the USENIX Association gave a Lifetime Achievement Award (Flame) to the Computer Systems Research Group at University of California, Berkeley, honoring 180 individuals, including Karels, who contributed to the CSRG's 4.4BSD-Lite release.

Later, Mike moved to BSDi (Berkeley Software Design) and designed BSD/OS, which was, for years, the only commercially available BSD style Unix on Intel platform. BSD/OS is a very reliable OS platform designed for Internet services. BSDi software asset was bought by Wind River in April 2001, and Mike joined Wind River as the Principal Technologist for the BSD/OS platform.

In 2009, Mike was Sr Principal Engineer at McAfee. In 2015 he worked for Intel and later for Forcepoint LLC.