On the contrary, rather (as a regular adversative conjunction, introducing a word or clause in contrast or contradiction with the preceding negative clause or sentence).
I am not rich but [I am] poor not John but Peter went there.
However, although, nevertheless, on the other hand (introducing a clause contrary to prior belief or in contrast with the preceding clause or sentence).
She is very old but still attractive.
Except that (introducing a subordinate clause which qualifies a negative statement); also, with omission of the subject of the subordinate clause, acting as a negative relative, "except one that", "except such that".
I cannot but feel offended.
Without its also being the case that; unless that (introducing a necessary concomitant).
It never rains but it pours.
Except with; unless with; without.
Only; solely; merely.
Until.
(following a negated expression of improbability) That.