Complex sentence: Mark Millar wrote most of the first 33 issues, followed by Brian Michael Bendis for 12 issues, Brian K. Vaughan for 20 issues, and Robert Kirkman for 28 issues.
Split into simpler sentences: Mark Millar wrote most of the first 33 issues. He was followed by Brian Michael Bendis for 12 issues, Brian K. Vaughan for 20 issues, and Robert Kirkman for 28 issues.