A person who maniacally controls the schedule of a group gathering or event to the point where everyone else wants to kill them.
This person is particularly rampant during family events and the hectic holiday season.
"Guys, we need to be back by 4pm or the baby is going to miss his nap. Do you have your shoes on yet? Were leaving in 3 minutes. I'm going to wait in the car" * door slam *
- "Looks like Schedule Nazi is back."
- "With a vengeance."