Incompetent admins and migration saboteurs
Last job had 'em both - mostly "senior" academics.
My predecessor had been sacked 18 months before (I'd have to tell that tale as AC as the circumstances were fairly unique and quite spectacular), and during that time a procession of individuals had helped out running things...
Including a senior academic who had managed to weasel his way in to privileged access on several systems. Can you say "personal fiefdom", children ?
This individual came to give me the "Do you know who I am ?" routine when I changed all the superuser passwords and locked him out. He took this to be a declaration of war, and questioned EVERY decision I made from that point, until his boss told him to shut up and let me get on with what they paid me to do.
He also tried the "migration saboteur" routine on a number of upgrades, at one point even trying to set up a "secure" intranet for senior management on his personal workstation. You guessed it, security by obscurity and no authentication whatsoever.
HE folks will also be familiar with the concept of the "central compute server" - usually some crusty old VMS or proprietary Unix box that's been around since the early days of the IT service. Even if you can provide better alternatives for everything it offers, people get very fond and possessive of such old systems, and decommissioning can be a nightmare. Especially when the senior profs start pulling rank and send complaints up the management chain. Last one of those took me the best part of a year to kill (the server that is, not the profs), despite the fact that most of the profs who wanted to carry on using it had *laptops* with more compute power at their disposal.
Admittedly, Pine 1.ancient was still a nicer UI than the Lotus Notes client, but let's be honest, that's not difficult.