Funnily enough Samael was the OG Satan before a mistranslation of Venus (as in the planet/celestial body) caused Lucifer to take a life of its own. That snake in the Garden of Eden? Was Samael, or Samael's steed.

And the OG (read: Jewish) Satan was more or less an accuser or prosecutor. God's Prosecutor, basically, and Samael in some traditions was considered the head honcho of the "Satans".

So, quite a fitting name for the fallen angel who ended up becoming High Prosecutor of Hell.