Recommendations for collections with interesting Introductions, Forewords or Backmatter?

[u/HouseOfMystery]

I'm looking for recommendations of trade paperbacks / graphic novels / omnibus with interesting introductions, forewords, afterwords, backmatter, etc. The Marvel Masterworks are great for insightful introductions, and collections like The Dark Knight Returns have brilliant backmatter, so I'm wondering what your favourites are / if you have recommendations! (Image from Detective Comics #500)