Sir Arthur Osmond Wynn Williams JP DL (17 March 1849 – 28 January 1927) was a Welsh Liberal Party politician.

[1] Williams grew on the family estate Castell Deudraeth and was educated at Eton.

[3] Williams served as Justice of the Peace and Deputy Lieutenant for Caernarvonshire, Chairman of Quarter Sessions for Merioneth, and constable of Harlech Castle.

In 1909, he was created a baronet of Castell Deudraeth and Borthwen,[4] and from 22 March 1909 to 28 January 1927, he served as Lord Lieutenant of Merionethshire.

Together, they were the parents of six children, including:[7] Lady Williams died on 10 August 1926.