sidekick, office worker, victorian clerk, author, journalist, or graphic artist.
actually, now that i think about it, the clean-shaven ones could be suitable for serious roles, so i guess i'm probably not good at judging someone's suitability for a role based on a headshot. ;)
oscar wilde plays, anything with received pronunciation really!
you have a lot of gravitas and weight (in terms of personality, not physically!). you can appear quite calm and approachable. characters that require intelligence and responsibility suit you.
from 4, i would cast you as a clever villain character. possibly even a tough love interest.
as you've outlined in your brackets above - i'd agree with those roles.
serious - moody - intellectual. you could do dark. you can do quirky.