Favourite eldritch abomination?

[Froge]

What's your favourite eldritch abomination? Can be from any book / film / game / medium of entertainment, etc.

For me, I would say Walpurgisnacht. It has a very nice aesthetic design and can be attacked through conventional means, such as with guns, but it is thoroughly unkillable. It has a very interesting laugh (it makes interesting bell / wind chime sounds in general) and is just generally a really disturbing / crazy thing.

The town of Silent Hill is a close second.