Robert Kirkman books in order
30 books in the catalogue, about 178 hours of reading in all; the shortest takes 2 hours and the longest 20 hours.
2 series and 7 standalone books in the catalogue.
The Walking Dead
32 books 1 Days Gone Bye length not known
2 Miles Behind Us length not known
3 
Safety Behind Bars 2.5 h 4 The Heart's Desire length not known
5 The Best Defense length not known
6 
This Sorrowful Life 2.6 h 7 
The Calm Before 2.5 h 8 
Made to Suffer 2.5 h 9 
Here We Remain 2.5 h 10 
What We Become 2.5 h 11 Fear the Hunters length not known
12 Life Among Them length not known
13 Too Far Gone length not known
14 No Way Out length not known
15 
We Find Ourselves 2.4 h 16 
A Larger World 2.5 h 17 Something to Fear length not known
18 What Comes After length not known
19 March to War length not known
20 All Out War (Part One) length not known
21 All Out War (Part Two) length not known
22 
A New Beginning 2.5 h 23 Whispers into Screams length not known
24 Life and Death length not known
25 No Turning Back length not known
26 Call to Arms length not known
27 The Whisperer War length not known
28 
A Certain Doom 2.5 h 29 
Lines We Cross 2.5 h 30 New World Order length not known
31 
The rotten core 2.5 h 32 Rest in peace length not known
The Walking Dead
9 books 1 
The Walking Dead: Rise of the Governor 5.5 h 2 
The Walking Dead: The Road to Woodbury 5.1 h 
Robert Kirkman's The Walking Dead: Return to Woodbury 5.3 h
The Walking Dead: Rise of the Governor 5.5 h 2 The Walking Dead: The Road to Woodbury 5.1 h 3 The Walking Dead: The Fall of the Governor length not known
3 The Walking Dead: The Fall of the Governor (Part 1) length not known
4 The Walking Dead: The Fall of the Governor (Part 2) length not known
5 Robert Kirkman's The Walking Dead: Descent length not known
6 Robert Kirkman's The Walking Dead: Invasion length not known
7 Robert Kirkman's The Walking Dead: Search and Destroy length not known
8 Robert Kirkman's The Walking Dead: Return to Woodbury 5.3 h Standalone books
Collected editions
Volumes that gather several of the books above.
The Walking Dead Volume 2 2.5 h 
The Walking Dead, Vol. 1 2.6 h 
The Walking Dead, Vol. 4 2.5 h 
The Walking Dead, Book One 5.6 h 
The Walking Dead, Compendium One 20.0 h 
The Walking Dead, Vol. 12 2.6 h 
The Walking Dead, Vol. 13 2.5 h 
The Walking Dead, Vol. 14 2.5 h 
The Walking Dead, Compendium Two 19.6 h The Walking Dead, Compendium Three 20.0 h