Big bug in my bedroom, please identify. (pic)

[SplitPeach]

I found this between the loose floorboards & now I'm having visions of my joists looking holey like cheese... Is this one a friend or foe?

I think its just a normal beetle.

google black beetle and see if it matches.

Stag beetle?

Definitely just some kind of garden beetle rather than woodworm etc

That's a non-damaging ordinary beetle.

It's a darkling beetle. Major feature of my childhood - they're fabulous.