Lieutenant-Colonel William Blacker (1 September 1777 – 25 November 1855) was an Irish British Army officer and Member of the Royal Irish Academy. He published under a variety of pseudonyms, and his works are sometimes misattributed to Valentine Blacker, also a Lieutenant-Colonel.
- Put your trust in God, but keep your powder dry.
- Popularized by Blacker in the poem "Oliver's Advice", published under the pseudonym Fitz Stewart in The Dublin University Magazine, December 1834, p. 700; where the quote is attributed to Oliver Cromwell (hence the poem's title). The repeated line in the poem is "Put your trust in God, my boys, but keep your powder dry."