First appearance = All-Star Squadron #4 (December 1981)
From Who's Who: The Definitive Directory of the DC Universe Vol. VII (September 1985):
First appearance = All-Star Squadron #4 (December 1981)
From Who's Who: The Definitive Directory of the DC Universe Vol. VII (September 1985):
Dragon King only fought the All-Star Squadron in issue #4 of that title, but his power over them was referred to again in issue #21 (May 1983).
Dragon King also appeared in the Stars and S.T.R.I.P.E. series
(this page from issue #5, cover-dated December 1999):