agree with kenri there, nothin' wrong with a golem. one of the entries, quite literally, is a giant metal ball.
http://mpfc.wikidot.com/the-hyperorb
i don't know what you have that didnt' sound very fun' so i can't comment there, but golems can be fun. they aren't human so their weaknesses or what kills 'em is ??? and depends on the creator.
updating tonight, should be able to get through everything just fine. but yeah, if you've got an idea, by all means, post.
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"Maybe it's a tentacle, molesting the planet itself. - Aschen Brodel.