There were cartoonists that supported hibernophobia and irish essayists that contested racism, but during the 17th-19th centuries were there any writers who were vehemently prejudiced against irishmen in their writings?
Not published in his lifetime, (and not intended to be published at all) but Thomas Carlyles Reminiscences of my Irish Journey in 1849 makes horrific reading as an example of the attitudes of the supposedly enlightened elite towards the Irish at the time. Here's his view on Famine relief 'makework':
"Can it be a charity to keep men alive on these terms ? In face of all the twaddle of the earth, shoot a man rather than train him (with heavy expense to his neighbors) to be a deceptive human swine."
Bear in mind that Gavan Duffy had brought Carlyle to Ireland in the hope of enlisting his support, as an influential establishment figure likely to be sympathetic to the Irish cause. If this was the case, can you imagine what others attitude must have been like?