Since I don't own the rights to Harry, I can't post a pattern. However, I will explain some of the basic techniques I used to create the dolls. I ended up doing a few new things for these dolls that I had never attempted before.
The bodies: I used a basic mushroom body shape, like the body I made for my Nativity dolls. Hagrid needed to be bigger so I added stitches to make him fatter and added extra rounds to make him taller. For Dumbledore, I didn't add extra stitches but I did add extra rounds.
The hair: This was my biggest challenge as I had never done hair on an amigurumi doll and it took a lot of experimentation. I think I will do a separate post with photos of the methods I used, but for now I will summarize by saying that for Hermione, Dumbledore and Hagrid's hair as well as the two beards, I crocheted a "wig cap" then threaded yarn through the spaces between stitches. I put glue on the underside of the cap so the hair wouldn't get pulled out. I pulled apart the strands of each yarn then used a wire brush to gently brush the yarn so it got fuzzy (except for Hermione, I didn't brush her hair out). I then attached the cap to the head. For Harry and Ron, I embroidered the yarn directly on to their heads.
The robes and Hagrid's vest: I started with my pattern for Joseph's robes and just added sleeves by picking up stitches around the arm holes and then crocheting in a spiral until they were long enough. Hagrid's vest was a short version of the robe without sleeves.
Scarves: I experimented with crocheting and knitting ties and scarves out of embroidery floss but when nothing turned out how I wanted, I switched to regular yarn and a homemade four-stitch knitting Nancy to make the i-cord scarves (this could also be done by using the double pointed knitting needle method, see this video).
Details: The faces and details were embroidered with embroidery floss. The eyes were safety eyes. Dumbledore's hat was a simple cone.