I thought my husband could be Harry Potter, and our toddler could be Hedwig, his owl.
And at the last minute, I thought our dog, Gus, could be a little Dementor from Azkaban.
I started first with the Snape costume. Well, let me say, I started doing the research. I will admit that I cannot sew. Or should I say, I can't sew well. And sewing straight seams (say that 5 times fast) is virtually impossible for me (at this time). So I knew I had to get help.
I enlisted the help of my very talented aunt. We had found various people online who had already tackled this costume and got a few ideas. She picked the pattern for the jacket and modified a pattern for the outer academic robes. She made the academic robes from a black bedsheet!
I bought a men's white button down dress shirt ( a bit larger than necessary), so the sleeves would be long enough to peak out of the cuffs of the jacket. I found a remnant of cloth from the fabric store and hand hemmed it so I could use it as a cravat/neckcloth. I used the mail coach/waterfall method of tying it as mentioned here in this pdf file. I had a bit of a time matching the pants with the closest shade of black and type of cloth the jacket was made - but it was pretty good. I think I may still want to take in the sleeves of the jacket more and the lower leg of the pants to make it more like the movie costume, but that may have to happen in the future when I have a bit more cash. I eventually grew my hair out and even dyed it to a very dark black.
I love it! Here is a pic of me wearing the costume (before I changed my hair color).