Nobody else mentioned the James Blish episode adaptations from the 70s......twelve books, plus a 13th with the Harry Mudd episodes and a third Mudd tale all written by his wife following his death. The earlier you go back in the series, the more liberties are taken with certain plots, with some very significant changes. Blish's MENAGERIE adapts only the Pike flashbacks and not the Kirk-Spock framing story. Blish thought doing both was unfeasible, though it wouldn't surprise me if several fans had attempted if not succeeded the assignment.
Since I'm above all else a 70s collector, my other TREKS consist of the Concordance, the Compendium (70s and 90s versions), SPOCK MUST DIE, the Foster Logs and I AM NOT SPOCK UNTIL THE SECOND BOOK.
As I remember, Blish used shooting scripts, and sometimes earlier versions than what was filmed, to do his writing from (from which to do his writing?). Hence the differences from what we saw on film - I imagine that's the reason for the occasional title changes as well - such as 'The Unreal McCoy' and 'The Last Gunfight'. I have them on the shelf too, along with the fotonovels, but it's been ages since I read them.