Final answer:
Samuel Taylor Coleridge was the literary figure who took opium for rheumatism, which influenced his poetic work. His most famous work reflecting opium's influence is 'The Rime of the Ancient Mariner.'
Step-by-step explanation:
The literary figure who was addicted to opium, which he had begun taking for rheumatism, and whose literary "pieces" are often attributed to opium-induced visions, is Samuel Taylor Coleridge. Coleridge was an English poet, literary critic, philosopher, and a founder of the Romantic Movement in England, alongside William Wordsworth.
Coleridge's addiction to opium significantly influenced his works, which are known for their imaginative themes and meditative nature. One of his most famous works, 'The Rime of the Ancient Mariner,' is believed to reflect his opium-inspired dreams. The poem's dreamlike and fantastical images bear the hallmark of Coleridge's use of the drug as a form of self-medication.
In contrast to Coleridge, poets like John Keats, Percy Bysshe Shelley, and Lord Byron also led dramatic lives but had different experiences and substances influencing their works.