This is a much darker story than I normally post.
Only 3 weeks ago, I would have rated it C & never bothered to write this post. I'm sure I'm reading more into it than author intended, but the "beast" in this story thinks too much like the terrorists involved in Bombay attacks a fortnight back; at least two of them who talked to a news channel using victim's phone during the (I think first day of the) siege.
PS: This video recording (I cannot see the video on my PC, but looks like others are able to see) is of the first of the two calls (in Hindi) that were aired by India TV; I could not locate the second one online. This was the call that convinced me we were dealing with Pakistanis - the man claims he is from Hyderabad in the South, but language, accent, & the words used are instant give away. And the content of the talk felt so much like the "beast" in this story (second call also felt like this "beast" - to my biased mind, at least).
Story summary.Narrator is modeled after werewolves - he can transform himself into a tentacled "beast" that hunts hapless people in the city at night, & kills for no reason but that he cannot help it! He also eats some of them. And narrator seems to have some sort of split personality - beast & the man who becomes beast have distinct though related personalities.
Fact sheet.First published: Fantastic, August 1975.
Download full text from Internet Archive.
Included in Ellen Datlow's Sci Fiction classics.