Major or minor enemies alike, here's a list:
Other people (sorry)
Cats or Dogs depending on view, rats otherwise
Spiders (little B*****ds)
Cockroaches (indestrucable)
Aliens (invasion, durp?)
Coffee tables in the dark (thump aaaaahhhhhhhh!!!!!! whuthumb).
noobtubers
shadows (shifty fellas)
Pheasants (tell me otherwise when you almost step on one and it flys into a passing car causing a crash)
Amnesia The Dark Decent.
Stumble (preventing so much progress)
Trolls (damn them and their under the bridge homes)
Trolls (damn them and their under the bridge homes with broadband)
MMORPGs
backward hats
The flys on your jeans.
flys
Disease
Lack of Cake
Lack of Pie
Lack of food all together.
Thirst
No fuel for 10 miles signs, when you're on empty.
Blindfolds
Deforestation
The morning after.
Morning Glory.
Math
Our fragile skeletons.
Rap
Value added Tax
Religion (in a way).
Karma (knew I should have given that guitar playing tramp some money)
Really sharp toothpicks
Early mornings
and
of course
Homework. Don't say just cos you're all grown up you don't get it. If you really don't you're not being paid enough.