Who among the following was famous as a diarist? Who among the following was famous as a diarist?

The correct option is John Evelyn.

John Evelyn (1620–1706) was a prominent English writer, gardener, and bibliophile, now best remembered as a diarist alongside his contemporary Samuel Pepys. His diaries, which spanned his entire adult life from 1640 until his death in 1706, provide an invaluable first-hand historical account of major events in 17th-century England, including the execution of Charles I, the Great Plague of London, and the Great Fire of London.

Let's briefly look at the other options to understand why they are not the primary answer:
- John Bunyan is famous as a preacher and the author of the Christian allegory The Pilgrim's Progress.
- The Earl of Rochester (John Wilmot) was a notorious Restoration poet and courtier famed for his satirical and bawdy poetry.
- Robert Walker was a well-known English portrait painter, notably painting Oliver Cromwell and other parliamentarians during the Commonwealth period.