1786 in Wales
- 25 December - Plymouth ironworks is leased to Richard Hill.
- The Kinmel estate is sold to the Rev Edward Hughes.
- Abraham Rees completes his edition of Chambers 's Encyclopaedia, and is elected a Fellow of the Royal Society in recognition of his work.
- Charles Pratt is created Earl Camden.
Arts and literature
- David Samwell - A Narrative of the Death of Captain James Cook
- Hester Lynch Piozzi - Anecdotes of the late Samuel Johnson, Ll.D., during the last twenty years of his life
- Helen Maria Williams - Poems
- William Ellis - Ychydig o Hymnau a Chaniadau Newyddion (collection of hymns)
- Benjamin Francis - Aleluia (collection of hymns)
- 6 April - John Humffreys Parry, barrister and antiquary (died 1825)
- May - John Jones, printer and inventor (died 1865)
- 22 June - Ellis Evans, minister and author (died 1864)