Since installing Nikon’s camera utilities, there is process called Nikon Monitor View Carbon which runs every time I log in. The thing which caused this to run wasn’t in the usual places for startup processes: /Library/Startup Items or ~/Library/Startup Items.
Well, this useful comment told me where it was. It’s an entry in /Library/Preferences/loginwindow.plist, i.e. the preferences for the login process.
Listening to Down To The River To Pray from the album “O Brother, Where Art Thou?” by Alison Krauss