The numbering in this series is quite chaotic. The Warren Companion (TwoMorrows Press, 2001) tries to make sense of it by finding enough issues to make the last issue numbers make sense but adds another level of confusion. They list the issues [in brackets] as follows:
[1] UFO and Alien Comix - listed at the GCD as U.F.O. and Alien Comix (Warren, 1977 series) #1 see
https://www.comics.org/issue/272790/.
[2] Future World Comix - listed at the GCD as Warren Presents: Future World Comix (Warren, 1978 series) #[nn] see
https://www.comics.org/issue/272783/.
[3] Starquest Comix - listed at the GCD as Warren Presents: Star Quest Comix (Warren, 1978 series) #[nn]
see
https://www.comics.org/issue/272786/.
[4] Galactic War Comix - listed at the GCD as Galactic Wars Comix (Warren, 1978 series) #[nn]
see
https://www.comics.org/issue/272784/.
#1 [5] Ring of the Warlords - listed in this series as issue 1.
#2 [6] Wanted: The Rook - listed in this series as issue 2.
#3 [7] Alien Invasion Comix - listed in this series as issue 3.
#4 [8] Movie Aliens Illustrated - no comics included and therefore not listed at the GCD.
#5 [9] Dracula '79 - no comics included and therefore not listed at the GCD.
#6 [10] Strange Stories of Vampires Comix - listed in this series as issue 6.
#7 - According to The Comics Reader #171, August 1979, #7 was to be Moonraker.
#8 [11] Pantha - listed in this series as issue 8.
#9 [12] Empire Encounters Comix - listed in this series as issue 9.
#10 does not exist.
#11 Horror Movie Yearbook 1981 - no comics included and therefore not listed at the GCD.
#12 Film Fantasy Yearbook 1982 - no comics included and therefore not listed at the GCD.
#13 Sword & Sorcery Comix - listed in this series as issue 13.
#14 Rex Havoc - listed in this series as issue 14.