During POA, there is this gryffindor boy who kept popping up every now and again with various lines like in Divination class he tell us about the Grim.

Who is this boy? I tried looking at the cast list, but I couldnt find him anywhere.

It seemed like he was meant to be in the trio's year... but why didnt they just give the lines to the person who plays Dean Thomas?

Im just curious to know who this boy is. Any ideas?