Rhosyr is a community in the far southern corner of Anglesey, Wales.

Rhosyr was the site of one of the courts of the 13th-century Welsh prince Llewellyn the Great.

It was rediscovered and partially excavated in 1992, with local activists currently (2017) seeking funding to uncover the remaining two thirds.

[2] Rhosyr elects a community council of fifteen councillors who, amongst other things, are responsible for maintenance of local footpaths and cemeteries.

However, since the 2013 local elections it has combined with neighbouring communities, Aberffraw and Bodorgan to form a larger ward, Bro Aberffraw, which elects two county councillors.