Witch is the last Diary of a Wimpy Kid?

As of my knowledge cutoff in September 2021, the latest book in the Diary of a Wimpy Kid series is "Diary of a Wimpy Kid: The Deep End". It was published in October 2020. There may be newer books in the series released after this date, so I recommend checking the official Diary of a Wimpy Kid website or a reputable bookseller to confirm the most up-to-date information.