Who was he in the scope of the story? Was he Jesus’ adoptive father ie the Joseph from the nativity scene?
No, Joseph of Arimathea was not the husband of Mary and the foster father of Jesus.
Who WAS he? He’s only mentioned a few times in the Gospels, and we don’t get a lot of detail. Matthew refers to “Joseph, a rich man from Arimathea, who had become a follower of Jesus.” Mark and Luke say he was a member of the Jewish Sanhedrin. John says only that he was a disciple of Jesus.
The only thing all four acounts agree on is that, after the death of Jesus, Joseph of Arimathea claimed the body, and had it placed in a tomb.
Joseph of Arimethea was not Jesus’ adoptive father–of that much I am sure. As I recall, he was a wealthy merchant in Jerusalem and a possible admirer of Jesus. I am also fairly sure that it was he who claimed Jesus’ body after the cruxificion (I believe he had to pay some sort of fine for this privilege–I think bodies were normally left to decompose on the cross) and that the holy sepulchre (where Jesus lay dead for three days) belonged to this Joseph.
This is what I recall from my “Bible as Literature” class, and is largely confirmed by this site:
http://www.britannia.com/history/biographies/joseph.html
There’s a legend that Joseph of Arimathea visited England three years after the crucifixion, that he founded Glastonbury Abbey as the first Christian church in the world, that he brought the Holy Grail with him, and that he’s buried there.
More about Joseph and the legend can be read here.
Wasn’t he killed by the legendary black beast of AAAAAAAAAAAAAAAAaaaaaaaaahhhhhhhhhhhhhhhhhhhgggggggggg… ?
Sorry, couldn’t resist 
So Joseph wasn’t Mary’s husband? Therefore he wasn’t a cuckold? Might this mean that Mary was a beard and they had an “arrangement”?
Different Joseph altogether. Try to pay attention.
Okay, but Mary Magdalene was still Jesus’s mom, right?
Sorry. The whole Joseph/Joseph of Arimathea thing had me puzzled for a long time too. Despite a church-going childhood, I didn’t realize they weren’t the same person until I was 20 or 21. I guess the sermons were never as clear on that point as they were about the difference between the Virgin Mary and Mary Magdalene.
I still don’t get the whole
Joseph: “How’d you get that way?”
Mary: “Um… God?”
Joseph: “Duh, okay. Oh yeah, Octavius the Centurion came by asking for you when you were at temple.”
At least she wasn’t goofy like Leda who claimed it was someone in the form of a goose or swan.