Impressive. Som of these concept arts were still unknown to me untill today. Thanks for sharing this.
Here are other concept arts and mockup I found for Hitman 1:
Source: https://www.behance.net/gallery/73009677/Hitman-2-Pre-Production
Source : https://www.behance.net/gallery/56261437/Hitman-UI?tracking_source=project_owner_other_projects
Source: https://www.behance.net/gallery/56261749/Hitman-graphic-design?tracking_source=project_owner_other_projects
Sorry for the eventual duplicates. Considering the number of concept arts you dug up, it somehow difficult to track all the duplicates.
Concept arts for Hitman 2 are also found on this site.