Letters and papers of Rev. John Williams (Ab Ithel) and his family, 1832-1898, comprising page-proofs of parts of Brut y Tywysogion (NLW MS 17163D); drafts and incomplete copies in manuscript of several of Ab Ithel's printed works, including Y Gododdin (NLW MS 17167E), The Traditionary Annals of the Cymry (NLW MS 17168E), Druidism (NLW MS 17169E), Brut y Tywysogion (NLW MS 17164E), and Annales Cambriae (NLW MS 17165E); contributions to the Cambrian Journal (NLW MS 17171E); his address at the Conwy Eisteddfod, 1861 (NLW MS 17187A); papers relating to his collation to the rectory of Llanymawddwy, 1849 (NLW MS 17189E); 'The Church of England independent of the Church of Rome in all ages' (NLW MS 17175B); sermons in English and Welsh (NLW MS 17184C); 'A few plain and practical Observations on Anglican Education' (NLW MS 17185B); the prize essay on the question 'whether the British Druids offered human sacrifices' by 'Hu Gadarn' (NLW MS 17173D); an essay entitled 'Traethawd ar Ddarganfyddiad yr America Gan Madog ab Owain Gwynedd, yn nghylch y ddeuddegfed ganrif' by 'Columbus' (NLW MS 17188C); an essay 'On the state of Agriculture and the progress of Arts & Manufactures in Britain, during the period & under the influence of the Druidical System' by Rev. John Jones, Llanllyfni (see Archaeologia Cambrensis, Supplement 1850) (NLW MS 17176E); 'Y Telynwr Cymreig, sef cyfarwyddiadau i ddysgu'r Delyn' by 'Dafydd Frenin' (NLW MS 17177F); four essays on 'Y manteision a ddeillia i'r Cymry o ddysgu yr iaith Seisnig' by 'Uthr Bendragon', 'Eiddil', 'Gwir Gymro', and 'Y cynyg cynta' 'rioed' (NLW MS 17188C); a 'History of Wales to the death of Llewelyn' (NLW MS 17178E); sections of a work on Christianity in Britain (NLW MS 17179E); letters addressed to Ab Ithel and also to his wife and daughters (NLW MS 17190D); press cuttings and extracts (NLW MS 17181E); sketches and medical and household recipes (NLW MS 17180C), and letters, 1884-1885, relating to the Ab Ithel Memorial Fund.