2000AD Prog 0001 Dave Gibbons

Dave Gibbons "Harlem Heroes" splash page from the very first issue.

This is the first appearance of John "Giant" Clay.
So...who is he, right? Well, this character ties into the world of Judge Dredd in a pretty interesting way.

I stole this bit from wiki-

>Judge Giant can refer to either of two fictional characters appearing in the Judge Dredd comic strip in 2000 AD. They are father and son. Their first names have never been given.

They are both descended from another 2000 AD character, 'Giant' (real name John Clay), who starred in his own series in 2000 AD, Harlem Heroes, which ran in progs (issues) 1–27 of the comic. John 'Giant' Clay made a cameo appearance in the Judge Dredd strip in prog 28. Since Judge Dredd himself did not appear in 2000 AD until prog 2, the Giant family's appearance in the comic predates Dredd's debut in his own strip.<