The Halloween franchise has been killing it among horror movie fans since the 1970s, with the series being comprised of numerous entries. Some of these are fairly contradictory, with the original scope and tone for Michael Myers and his surrounding mythology changing drastically in each film. This is nowhere more apparent than in one of the many anniversary "legacy" sequels: Halloween H20: 20 Years Later.
Source：https://www.cbr.com/halloween-h20-not-canon/
