A mod for OpenXcom Extended that adds a new Soldier type and two powerful Transformations. This expands and extends upon https://openxcom.mod.io/immortals-for-x-com-files by heelys, so Credit for the original Idea goes there :)

• changed starting units to Untouchables only: Vanilla XCom 1/2: 4, The X-Com Files: 2
• balanced salaries: purchase 120k, ranks 40k/60k/80k/100k/120k per month
• rank list ist now denoted with a (U) suffix for Untouchables using rankStrings
• changed resurrection timer to 28 days modified by difficulty,
  • the waiting time can be cut short with regeneration

OpenXcom Extended 7.8 is needed at at least for the base games.
Untouchables 1.1 needs at least The X-Com Files 2.7, Version 1.2+ is for The X-Com Files 3.3.
The Arsenal Additions Compability AddOn is compatible from 0.8.1b and upwards.

mod.io: https://openxcom.mod.io/untouchables

• A new race of Soldiers: (Cost $120k)
  More expensive troops, but they come with higher basic Stats and growth potential

• Get a Headstart
  You start a new game with 2 Unstoppables already in your starting Squad

• New Transformations
  Two Expensive Procedures with a mandatory reconvalescence of 1 day

  • Regeneration: (Cost $50k / $20k for X-Com Files)
    Gets a wounded Soldier back on their feet
  • Resurrection: (Cost $250k / $100k for X-Com Files)
    Completely revives a dead Soldier

Extract the four folders from the downloaded archive into your OpenXcom Extended/user/mods folder.
Since OpenXcom reads a tag from the metadata.yml, only the correct mod will show up in the mod list, so you can just drop them all in.

For anyone wondering what the Folders are for:

• UntouchablesXCOM1 is for UFO: Enemy Unknown / X-COM: UFO Defense
• UntouchablesXCOM2 is for X-COM: Terror From the Deep
• UntouchablesXCF is for the highly recommended The X-Com Files mod https://openxcom.old.mod.io/the-x-com-files
• UntouchablesXCFA is a compatibility addon for X-Com Files Arsenal Additions https://openxcom.old.mod.io/x-com-files-additions

Since all the mod data is just a bunch of clear text YAML formated .rul files, you can dig around and change things to your hearts content.
OpenXcom Ruleset Reference: https://www.ufopaedia.org/index.php/Ruleset_Reference_Nightly_(OpenXcom)