The first Warlord series ran for 133 issues, from 1975 to 1989, with Grell both writing and drawing the first 52 issues; his then-wife Sharon Wright ghost-wrote issues #53-71, and Grell stopped drawing the interiors after issue #59. Grell also wrote a six-issue Warlord miniseries in 1992 and a 16-issue ongoing series that launched in 2009.
Grell was also one of the artists for Green Lantern/Green Arrow: Hard Traveling Heroes and wrote an introduction for the 2024 omnibus (see “‘Green Lantern/Green Arrow: Hard Traveling Heroes’ Omnibus Collects Entire Saga for the First Time”).