US Heavy Metal editions are described here.
Requiem, Chevalier Vampire is a series created by Pat Mills and Olivier Ledroit, following a dead WW2 German soldier, Heinrich, stumbling across the chaos of Resurrection, a reverse world where time runs backwards, and where he discovers he is a vampire.
Publication of Requiem, Chevalier Vampire started in November 2000, with usually one volume published per year up to volume 10. Each story shares the same type of opening sequence, introducing a character through a flashback, and crossed looks 'Sergio Leone' style (there are other references to the great Italian filmmaker in the series). The series is scheduled for 13 volume and currently 11 volume has been issued, and no precise date has been given by the authors for the next volume (at least not until 2019/2020, source).
In fact the production was in hiatus since volume 11 because Nickel editions was not able to sustain the publication and Nickel has ceased to exist altogether officially in April 2015 (source). In late 2015, the authors have confirmed that for now on, it will be Glénat that will handle Requiem publication.
Glénat have initiated their take on publishing Requiem by launching a reprint of the series with new covers and a few extra, starting in January 2016 with volume 1.
The Nickel era: here is the collection originally published by Nickel (click on the captions to reach the individual files of each volume):
Note that these Nickel volume have been reprinted throughout the run. Subsequent prints of volume 1 has been improved in terms of color contrast. Volume 10 has been originally published with three different covers (see vol 10 file for more details).
Every 3 volumes, Nickel has published a limited box set edition (where only the slipcase and a bookplate are exclusive).
The Glénat era: so far there are three volumes reprinted in January, March and May 2016, with new wraparound covers. This hardcovers collection is slightly wider horizontally, allowing few millimeters of extra art on each side of the pages. Each volume also includes 8 pages of extra art (in each file I will try to pinpoint their origin).
|vol 7||vol 8||vol 9|
If you want to know more on that series, don't hesitate to go to the non so unofficial site where there is also an English section.