Does there exist a mod to allow you to see other players/your corpse on the minimap, the way you can in D2? My friends and I have played through both 2 and 3, but could never get 1 to work. With the GOG release we were finally able to, only to discover that it is impossible to find each other or our own corpses. It made it a very not fun experience any time someone died or took a wrong turn and suddenly the party was broken up. Surely someone has made a mod for this?

In D1, your corpse is removed when you restart in town, so there's nothing to show. Your items stay where they fell. Such a mod, if it existed, would need to record the location of your corpse while you are dead, then show it to you after you restart in town.

I am not aware of any such mods being available anymore. I believe the player-finding part once existed as a cheat for griefers looking to hunt down other players. You could, of course, use it constructively, if you could find it again. It would only cover finding live players though, not death sites.

If you use torch you get alt highlighting for items on the ground and can see other players on the mini map as well... The only place I am aware of getting it right now is on the D1Legit discord server:

https://discord.gg/NeAwSEP

Look under "Check our sponsers" / D1LEgit-blog ... GainTrain posted a download link to the .zip file it can be temperamental so ask for help on the discord if you cannot figure it out.

As far as your corpse... there is no corpse like in D2, but all of your items will drop on the ground. Try to remember where you died and you can use your minimap (look for portions where the exploration stops) to better pinpoint your items that fell on the ground during death.