The common denominator is that at least some (and preferably the majority) of their writing is imbued with a Catholic religious, cultural or aesthetic sensibility.
The most notable figures are Cardinal Newman, a convert, one of the leading prose writers of his time and also a substantial poet, and the priest-poet Gerard Manley Hopkins, also a convert, although most of the latter's works were only published many years after his death.
In the early 20th century, G. K. Chesterton, a convert, and Hilaire Belloc, a French-born Catholic who became a British subject, promoted Roman Catholic views in direct apologetics as well as in popular, lighter genres, such as Chesterton's "Father Brown" detective stories.
In America, Flannery O'Connor wrote powerful short stories with a Catholic sensibility and focus, set in the American South where she was decidedly in the religious minority.
There was a strong Catholic strain in 20th-century French literature, encompassing Paul Claudel, Georges Bernanos, François Mauriac, and Julien Green.