Quote: dellas @ February 2 2012, 9:15 AM GMTA female maybe Queen in Black Adder.
Good one!
Top Sitcom Monster? Page 5
Quote: zooo @ January 29 2012, 4:01 PM GMTAw, but he's lovely really.
I've got some ice pops in the freezer in my basement
I'd have to say
Alan B'Stard
That ARP warden out of Dad's Army
Chris Morris (although technically speaking not a sitcom star as such) in Brass Eye
Victor Meldrew (I wouldn't want to live with him) 
Cartman from South Park, Gil from Nighty Night, Chris Finch in The Office was a good shout, and many many sketch characters.
Most of the best ones have been mentioned. Someone mentioned Hitler in 'Heil Hitler'. He would also count in Dad's Army, 'Allo 'Allo! and Goodnight Sweetheart as an evil unseen character.
How about Matron Hilary Loftus (Ricky Grover) in Getting On? A passive aggressive monster? Bishop Len Brennen in Father Ted. Tom Good in The Good Life (unintentional but come on!). Vicki in Saxondale. Duane Bansey in Spaced. Den Perry and Keith Lard in Phoenix Nights. Marion and Geoff in......Damn! I've forgotten the name of the show!
Quote: DougWonnacott @ March 31 2012, 5:40 PM BSTTom Good in The Good Life (unintentional but come on!).
Not quite a monster but I do see your point, Tom is the driving force behind all the Good's mishaps and general state of penury, for sure. And an irritating one.