The surprising lack of knowledge regarding his existence is a testament to his discretion.
Shady Sam is a merchant who sells poison, lockpicks and skooma.
Nordinor is certainly the more prominent of the two, given that he inhabits one of Cyrodill’s cities.
Unlike the majority of Oblivion’s NPCs, Shady Sam doesn’t feel the need to eat or sleep.
He just occupies his post, dealing skooma to interested passersby.
It’s clear evidence of Shady Sam’s work ethic that he can maintain this schedule indefinitely.
This is because Shady Sam isn’t far from where the player exits the sewers following the prologue.
If you didn’t know about Shady Sam, now you do.
He’s a very effective lockpick dealer if you might be bothered to find him outside the walls.