Interesting in this context is completely divorced from morally good/bad. Could be any group from any area at any time in history. I’ll start with a few, followers of the cult of pythagoras, contemporary black Hebrew Israelites, antiracist skinheads and the Amish (neo-luddites in general). Don’t be racist or a prick to other people discussing.
Knights Templar, one of the oldest secret societies that may or may not still exist.
They most definitely still exist today. I studied in a private Jesuit run school. We were taught survival skills in the cubs & scouts. Then we were taught defensive combat skills.
You could also enroll in fencing & marital arts, but I had other things on my mind at the time.
Very historically interesting group.