George Eric Mackay was an English minor poet, now remembered as the sponging half-brother of Marie Corelli, the best-selling novelist. Mackay and Corelli, born Mary Mackay, were the children of Charles Mackay, by different mothers.
As a poet he is described as "execrable", and reliant on Corelli's promotion of his works. Mackay achieved some reputation in his time for Letters of a Violinist. It sold 35,000 copies; he repaid Corelli's efforts by implying he wrote her novels.
A 1940 biography of Corelli, George Bullock's Marie Corelli: The Life and Death of a Best-Seller, hinted that the relationship was incestuous; this has generally been discounted, though Eric's laziness and lack of scruples are acknowledged. This was an old rumour, attributed to Edmund Gosse.