Spies without question. That's not limited to governments, spying in the
realms of trade and manufacturing - after that was no longer identical with governments, say since the end of the Bronze Age - has been going on in the "private" sector for millennia.
But there is one difference: "external" and "internal". Kleptocracies and authoritarian systems (
huge overlap there) may have needed (and need) more of both internally than externally. Robber barons (aristocratic or not) never sleep well.
Assassins - as in someone killing a foreign leader after the demise of the Middle Eastern sects a bit after the expulsion of the last Christian crusaders from Akko in now northern Israel - not quite so much of a threat as may be assumed. I definitely have the impression that far more assassinations were carried out by "natives", subjects of the ruler of the time, than by foreign agents. Which would have to have been "natives" in the pay of foreign
organizations anyway. Especially (but not limited to) the kleptocrats etc. I mentioned above needed internal spying to keep them safe from the, say 98% of their population who would have gladly done them away. More recently (say post-WW II) those kleptocrats have managed to hightail it out of their countries before getting killed ...