There have over the years been many television advertisements which featured horror or monsters even if the actual product was nothing to do with the theme. Ones that come to mind include the Holston Pills ads, the one with Griff Rhys Jones incorprated in a scene with Peter Cushing, Haywards Pickles with Vincent Price, Ted Rodgers [of 321 fame] as a werewolf in the Mountain Dew ads [Soocckk!!], the Electricity ads with several classic monsters including Frankenstein's monster and family. I am sure there are many more. I'll post more when I can think of them. The ones I remember that advertised Horror/monster type products included a vampire in top hat walking into a dungeon or lab, the vampire was played by Frank Thornton [Are you being served] this was a advert for Smith's Horror Bags, there was the Monster Munch ads, one or two for the 80's Scream comic and I am sure many more. If you think of any others, please let me know in the comments section, especially if you know where these ads can be seen.
For the moment here is a ad from the 1970's featuring Frankenstein's monster and Dr. Frankenstein advertising Hoff Meister lager. http://www.visit4info.com/details.cfm?adid=14581&type=coolad&startrow=31