Thanks to Chaucer we have such words as intellect, galaxy, famous, bribe, accident, magic, resolve, moral, refresh and resolve.
John Lydgate gave us opportune and melodious. Bible translator John Wyclif was responsible for chimera, civility, puberty and alleluia. Ben Jonson brought strenuous, retrograde and defunct into the language. Sir Philip Sidney produced hazardous, loneliness and pathology. John Skelton introduced idiocy and contraband.
Robert Burton, the 17th century scholar, gave us electricity, therapeutic and literary. Novelist Fanny Burney is credited with grumpy, shopping and puppyish. Lawrence Sterne brought lackadaisical, muddle-headed and sixth sense into the vocabulary. Poet Samuel Taylor Coleridge popularized cavern, chasm, tumult and honeydew. Thank Sir Walter Scott for blackmail, awesome, gruesome, guffaw, faraway and uncanny.
As I've suggested, these people did not necessarily invent all these words. In many cases, they may have heard words in conversation that they then incorporated into their own writing, or they may have even seen these words used in books that have not survived. In other cases, they borrowed words from other languages and simply made English words out of them. That these people have so many words accredited to them has a lot to do with how prominent and influential the literature produced by them was in their own time and since. Many people create words that die on the vine simply because they are not written down or, if they are, they are written in literature that generates little attention and does not pass the test of time.
Even the words introduced by the above individuals did not always gain acceptance with the public. Skelton, for example, called a clumsy person a knucklybonyard and a fool a boddypoll. Perhaps it's a good thing the influence of him and the others went only so far.