They may not have all been Thalmor agents, but earlier, as I was leaving Whiterun as a werewolf, I ran into three Thalmor agents(no prisoner). I attacked them and then my entire compass lit up like a Christmas tree. Thalmor ambush, perhaps?

go to whiterun

BY SOLITUDE RIGHT?! same thing happended to me, i was crossing the bridge and he passed me by. I FORGOT ABOUT THAT!

Heh, I just got attacked by an Argonian... he attacked me with his fists... his inventory was full of beer, wine and Skooma

A couple other random encounter types I've recently seen:

-A "scavenger" standing over a couple dead Imperials and Stormcloaks, who attacks you on sight.

-3 Revelers on the side of the road, who offer you Honningbrew mead. If you happen to have one on you, you can share it, and a reveler will give you a "charmed amulet" which adds 25 carrying capacity.

i only got 1, guess the other two didn't make it

My encounters from the OP:

-A thief runs up to you asking you to hold an item he stole from a hunter.
-A skooma dealer offers to sell you some of the good stuff.
-Two children running up to me selling dwemer cogs and the location of a local dwemer ruin.
-Thalmor escorting a prisoner.
-Imperials escorting a Stormcloak prisoner.
-Hunters hunting.
-A dark brotherhood assassin trying to kill me.
-Hired thugs sent to kill me for thefts I've done.
-Three bandits claiming to be from the Imperial Legion who try to extort a bribe from me.
-Highwaymen, like in Oblivion, who ask you for money or they will attack.

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Different encounters:

-Orc looking for a good death

-Rich people on horseback with guards travelling

-Random people wondering to join the Legion/Stormcloaks

-Caravans which have been tipped over and loot taken/spilled... Case 1: Dragon did it wagon was charred, as well as bodies. A Horse which I could borrow was also present. Case 2: Wagon tipped, people killed, bandits near by.

-The Companions fighting the untamed wilds - Vilkas, Farkas, and Athis

-Bandits taking on larger game Mammoths or Giants.... they usually lose (I've never seen them win anyway)

- Animal(s) vs Other Animals(s)

- Travelling bards

I had an encounter with a thief and he said something along the lines of "hail nightingale i had a job go really well, here's your share" and he gave me 500 gold

Oh, hell yes, I forgot about that. I ran into Ria way up near Winterhold, trying to kill a frost troll (and failing). I saved her butt, and she told me to consider joining the Companions... if I thought I was "good enough".

I got some random encounters with people named after their race (imperial, breton, altmer,...) trying to kill me for no reason. I got no bounty, no murder or assault charges for killing them. They're all fairly powerful: they can use weapons and high level offensive spells and they're dressed with the best armor available at a certain level. One of them also rode a horse that became free to take after I had to put down his former owner.

Once level 30 is reached, it's possible to encounter Boethia cultists. Upon reading a book they carry, the Daedric quest pertaining this price is started.

Thalmor atacking Stormclokes

Three Imperial soldiers fighting with three Stormcloak soldiers.

After obtaining the Ring of Namira, you'll start encountering NPCs standing over a corpse that offer you the first bite.

A stray dog fighting off a pack of wolves that will fight alongside you if you save it.

a random thief was killed outside the riverwood trader and never despawned. i got tired of looking at it, and dragged down into the river and watched it float off.