Romanticism is a very broad term, one more indicative of a direction of thought than of anything that could be termed a school or belief system. The Romantic Movement begins in the 18th. Century in Germany, in the 18th. Century with Rousseau in France, and in the late 18th. Century in England. Historian Jacques Barzun characterizes Romanticism as a reaction, not against Reason (that near-God of the Enlightenment) but against the "cold" intellect (intellect divorced from emotion). Many of the major figures were scholars (Goethe, Coleridge, even Shelley) and quite fond of Reason, but also insistent on the reality of emotions.
In English literature the term is standardly associated with Wordsworth and Coleridge ("the first generation") and with Byron, Shelley, and Keats ("the second generation"). Such an association leaves out the earlier William Blake and Robert Burns, both clearly Romanticists. Likewise, such a limitation ignores the fact that Victorian Robert Browning would, not quite accurately, have considered himself a Romantic poet, and that such contemporaries of his as D.G.
Rossetti, William Morris, and A.C. Swinburne should definitely be labeled "Romantic."
Of course, the definition is further compromised by the continued, and continuing, existence of Romanticism. Critic Harold Bloom considers himself a Romantic. I am a Romantic, a sort of heir to the intellectual tradition of philosopher Henri Bergson and, particularly, of critic/philosopher/historian Benedetto Croce. I also remember once having a professor who considered himself an avid "anti-Romantic," and who insisted that Beat Generation writer Jack Kerouac was a Romantic and Romanticism was characterized by Kerouacian empty-headedness. I believe he was in error on both counts, and that he demonstrated only that his judgment and sense of intellectual rigor was as lacking as that of his "enemy" Kerouac, but I give the example as a note of the continuing debate regarding...