The shape of this skull suggests just one thing... TENTACLES!
There was a strange spate of CTHULHU graffiti around the Hyde Park area of Leeds in the mid-1990s. Chunky letters hinted that the stars were right and tentacles would soon be on their way. This was the last piece to survive.
I took this photo back in June 2004, when the paint was wearing thin. You can't really make it out at all anymore. When it was new the red paint gave the impression of boiling blood!
It was just off Hyde Park Road, around the back of where the Newlands pub used to be. The one that burned down in the 1995 riot.
All of the Cthulhu graffiti was done with letters in this style, usually with a thick outline. The biggest piece was along the wall of Royal Park School - the same one that's now an official graffiti wall. It just said CTHULHU in big reptile-green letters, six-foot high and forty-foot long!
Another well-known piece said CTHULHU RISING, this time in a sea-sickness inducing shade of blue. It was behind Prince's gym and you could see it on the way up Hyde Park Road. That piece disappeared when the building it was painted on was renovated.
Update: (16th December 2008) panoramio.com has a photo of the CTHULHU RISING piece. The building in the background was derelict for about a decade, and looks like just the place for some mad cultists (students live there now). The photo information at Panoramio dates it to 30th July 2008, but that's incorrect. The wall was replaced by garages when the house was renovated in 2005 or 2006.