Event books have become a big part of comic publishing in the 21st century, with Marvel and DC both embracing them as a big part of their year. Of the two companies, though, Marvel does a lot more event books than DC, using each one as a catalyst for yearly changes to their lines.

RELATED: Avengers Vs. X-Men: 5 Ways It Aged Well (& 5 Ways It Hasn't)

There are times, of course, when fans have gotten a bit tired of Marvel's reliance on event books, but that mostly happens when the event book is bad. When they are good, fans don't complain nearly as much and embrace the new directions. Marvel has had some truly great event books in the 21st century and some abysmal ones and let's take a look at the best and worst.

10 Best: Avengers Vs. X-Men

X-Men vs Avengers

Avengers Vs. X-Men was a risky proposition. Written by five different writers: Brian Michael Bendis, Jonathan Hickman, Ed Brubaker, Matt Fraction, and Jason Aaron, it pitted Marvel's two biggest teams against each other as the Phoenix Force headed to Earth. While it was kind of inconsistent, with the stylistic differences between writers sometimes apparent, it was still a very good story.

It especially ramped when five of the X-Men gained the Phoenix Force, becoming the Phoenix Five and doing their best to change the world until the Phoenix Force started to drive them mad. The book's art was also a huge asset, with John Romita Jr., Olivier Coipel, and Adam Kubert supplying some amazing visuals.

9 Worst: Secret Invasion

Secret Invasion (2008)

Secret Invasion, by writer Brian Michael Bendis and artist Leinil Yu, isn't as terrible as some of the other events on this list but that doesn't mean it's very good either. The story of the Skrull invasion of the Earth had a lot of potential that was squandered by the way the story was told. The first half of the book was way too slow and it kind of soured the whole thing.

RELATED: 5 Reasons House Of M Is Way Worse Than You Remember (& 5 Reasons It's Not Completely Terrible)

The other problem was Bendis's extremely wordy style of writing, emphasizing dialogue over the action, as well as a bunch of weird plot decisions he made. Yu's art was pretty fantastic, making up for a lot of the script's deficiencies, and the ending was very good but there are a lot of drawbacks to this story that held it back.

8 Best: Siege

Iron Patriot and Dark Avengers in Siege

Siege, by writer Brian Michael Bendis and artist Olivier Coipel, saw Norman Osborn and his Dark Avengers attack Asgard and the heroes of the Marvel Universe come together to stop him. It was the ending to the year-long Dark Reign status quo, which saw Osborn and the villains in charge of the Marvel Universe.

At just four issues long, Bendis didn't have the page space to indulge in his dialogue-heavy style and the event had very little of the characteristic boredom of Bendis written events. There are a lot of very cool moments in this book, like the Sentry killing Ares, the return of Captain America, and more. Coipel's art was a perfect fit for the story, making the action look great and capturing all the moments with aplomb.

7 Worst: Fear Itself

Fear Itself the Mighty

Fear Itself, by writer Matt Fraction and artist Stuart Immonen, was a Thor-centric event that saw the heroes facing off against the Serpent. While it was hyped pretty heavily, it was kind of a dud overall. There were some cool ideas in it, like the Serpent giving out Mjolnir-like hammers and pitting their bearers against the heroes, but overall the whole story is lackluster and forgettable.

Thor has some great villains, so the idea to use a completely new one is kind of mystifying and doesn't do the book any favors. On top of that, it didn't engender any kind of memorable status quo change. Most readers have little to no memory of it at all. Immonen's art was fantastic as usual, but it couldn't save this book.

6 Best: Secret Wars

Secret Wars

Secret Wars, by writer Jonathan Hickman and artist Esad Ribic, was the culmination of Hickman's Avengers run and saw the end of the Marvel Multiverse. Doctor Doom would step up, saving what was left and becoming God in the process. Of course, things would go on from there, as heroes thought dead returned to set things right and Doom became more and more unhinged.

Secret Wars was full of amazing moments and concepts, as only a book written by Hickman could have. Ribic's art gave the whole thing a regal look and feel. It's one of the rare Marvel event books of the '10s that is unequivocally loved and praised.

5 Worst: Age Of Ultron

Age of Ultron feature

Age Of Ultron, by writer Brian Michael Bendis and artists Brian Hitch, Brandon Peterson, Carlos Pacheco, Butch Guice, Alex Maleev, and Joe Quesada, saw Ultron taking over the world and Wolverine and Invisible Woman going back in time to change things and only making it worse. Not to be confused with the movie of the same name, the story had a great premise but bad execution.

At ten issues, Age Of Ultron was a long event and Bendis indulged his worst tendencies throughout, stretching everything out and leaving all the world-building for the alternate present to the tie-in books. The art was very good but this was just a bad event in general a great premise soured by length and execution.

4 Best: Civil War

Cap's Heroes versus Iron Man's heroes during Civil War

Civil War, by writer Mark Millar and artist Steve McNiven, saw the US government react to a superhero created tragedy by passing the Superhero Registration Act, and the heroes choosing sides, with Captain America being the leader of the side against the bill and Iron Man leading those who teamed with the government.

RELATED: Marvel: 5 Ways Civil War Aged Well (& 5 Ways It Did Not)

While Millar took some liberties with characterization, it all worked in the context of the story, even hitting on some of the real-life political issues of the day, like trading freedom for security. The book was action-packed and powerful and still holds up all these years later.

3 Worst: House Of M

House of M

This spot was a toss-up between House Of M and Civil War II, but House Of M gets the nod because it is way worse than most people remember.  The first time writer Brian Michael Bendis and artist Olivier Coipel teamed up, it saw Scarlet Witch change reality, making mutants the dominant species and the heroes trying to change things back.

It's hard to deny the impact House Of M had but going back and reading it is a chore, to say the least. The book is much too slow and boring, with Bendis butchering the characterization of most of the characters in the book. Coipel's art is great but it can't save this boring slog of a book.

2 Best: House Of X/Powers Of X

dawn of x: X-Men

House Of X/Powers Of X, by writer Jonathan Hickman and artists Pepe Larraz and R.B. Silva, undid years of damage to the X-Men that Marvel had done in a few short months in the summer of 2019. Introducing an entirely new status quo, with mutants forming their own nation on the mutant island Krakoa and the consequences of their actions.

Hickman shocked and surprised readers with every issue of each book, with each one complimenting the other and presenting an X-Men story unlike just about any that readers had ever experienced before. Larraz and Silva did a great job presenting all of Hickman's big concepts in all their glory.

1 Worst: Secret Empire

Secret Empire Image Cropped

The tragedy of Secret Empire, by writer Nick Spencer and artists Steve McNiven, Rod Reis, Daniel Acuna, and Andrea Sorrentino, is that it should have been amazing. The build-up was near pitch-perfect. Steve Rogers was an agent of Hydra and as planning to take over America.

Unfortunately, the book itself dropped the ball on everything. It was too long, fraught with delays, and generally disappointing. It's a shame because the book's message about the rise of fascism in America was timely. If this book had been done well, it would have a classic; it wasn't and readers were left with a bloated mess.

NEXT: Marvel Comics: 5 Reasons Civil War II Is Marvel's Worst Event Of The 2010s (& 5 Why It's Secret Empire)