Siambr or Y Siambr [] may refer to:
* Y Siambr, the Welsh Parliament or Senedd's debating chamber
**Tŷ Hywel (''Siambr Hywel''), its former, now youth, chamber
*Y Siambr (TV series), ''Y Siambr'' (TV series), an S4C game show
* Any
chambered cairn in Wales
*
Siambr Trawsfynydd, a mountain in West Wales
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