Mike Wilhelm is the assistant coach you should probably know by now but have almost certainly never heard of.
It is nothing short of amazing how long he has lasted in an organization that gets rid of coaches more frequently than a typical Game of Thrones book. Wilhelm started his tenure as a Bulls advance scout as part of Bill Cartwright's staff in the 2002-03 season. That was so long ago that current head coach Fred Hoiberg was still a player for the Chicago Bulls!
Wilhelm made it through the Cartwright, Skiles, Boylen, Del Negro, and Thibodeau eras and was the only assistant that Hoiberg decided to keep from Tom Thibodeau's staff.