Wrightson's first of a handful of stories for Marvel:

CHAMBER OF DARKNESS 7, "Gargoyle Every Night", 7 pages, Oct 1970.
Wrightson's 17th published story.

Wrightson also did covers for this issue, and for CHAMBER OF DARKNESS 8, Dec 1970, TOWER OF SHADOWS 8 and 9, Nov 1970 and Jan 1971.
And WHERE MONSTERS DWELL 8, March 1971 (Marie Severin pencils/Wrightson inks).

Plus a story for DC a month later, in UNEXPECTED 121, "The Hound of Night", 1 page, Nov 1970.
Wrightson's 18th published story.

Then Wrightson did 7 pin-up introductory pages for various stories in DC 100-PAGE SUPER SPECTACULAR 4, Jan-Feb 1971.
https://comiconlinefree.com/dc-100-page-super-spectacular/issue-4
Despite being number 4, it's the first of DC's 100 pagers, all reprint material except for Wrightson's contribution. Wrightson also did the cover, his first cover for DC.
Wrightson's 19th published mainstream work.

And CREATURES ON THE LOOSE 10, featuring Robert E. Howard's Kull, in "The Skull of Silence", 7 pages, March 1971.
Wrightson's 20th published mainstream work.



And While it's still in season, HOUSE OF MYSTERY 191, "Night Prowler", 3 pages, April 1971. Wrightson's 21st published mainstream story. A prelude to greater work by the Wein/Wrightson team.
Wrightson's 21st published mainstream story.

Followed in HOUSE OF SECRETS 92, "Swamp Thing", 8 pages, June-July 1971.
Wrightson's 22nd published story. And at only his 22nd story, Wrightson rose to superstardom as a comics artist. This was the single best selling DC title for that month, and editors were clamoring for Wein and Wrightson to continue the story and turn it into a series. Wein finally came up with the idea to follow the same theme with similar characters in a new series, while leaving this initial offering a stand-alone story.

After this, Wrightson only did another 18 stories for DC in this era, 10 of which were the award-winning SWAMP THING series (plus a lot of decorative covers and introductory splash pages), up till June 1974. Before he jumped ship and started working for the Warren magazines.