What is the name of the first published novel in 'The Chronicles of Thomas Covenant'?

The first published novel in The Chronicles of Thomas Covenant is Lord Foul's Bane, written by American author Stephen R. Donaldson.

Published in 1977, Lord Foul's Bane begins the first Thomas Covenant trilogy. Covenant is a writer diagnosed with leprosy who becomes socially isolated after his marriage ends and his community rejects him. After an accident leaves him unconscious, he awakens in the fantastical Land, where people treat him as a figure from prophecy.

The novel is followed by The Illearth War and The Power That Preserves, completing the original trilogy. Donaldson later expanded the setting with additional books, including a second trilogy and The Last Chronicles of Thomas Covenant. That larger publication history can make the series order seem confusing.

The Wounded Land is not the first novel: it is the opening volume of the second trilogy. The Illearth War and The Power That Preserves are later books in the original sequence, so Lord Foul's Bane is the single canonical answer to this question.