The best corpses requires some of the very specific body parts for autopsy. Some of which are the -2 red skull/+3 white skull and +3 red skull/+3 white skull Important Parts (Hearts, Brains, Intestines) which you will need to be collecting over the course of your playthrough. Prayer for Repose can be used to increase the tier of the corpses if you haven't already unlocked the highest tier corpses yet.

With the release of Better Save Soul DLC you can now modify your inferior Important Parts into +3 red skull/+3 white skull parts. It makes this entire process a bit easier but it requires a decent amount of Sin Shards to modify a part. I recommend using Prayer for Souls' thorough Cleansing as it significantly increases the number of shards you get from healing a soul. For a detail on the amount of Sin Shards required for modifying skulls on an Important Part to a +3R/+3W part look at the table below.


Examples:

-2 Red Skull/+3 White Skull Intestines:


+3 Red Skull/+3 White Skull Heart:

With the release of Better Save Soul DLC has added the ability to modify body parts which makes the current best possible corpses to increase to 26 white skulls. These modifications can be performed at the workshop in the Souls room. A list of the modified parts used in the method for making these 26 white skull corpses are listed in the table below.


With the addition of Marble sculpture VI and Marble grave fence VIII, the best possible decorations for a grave is now capping at a total of 26 decoration points making the best corpses for the graveyard to be an all 26 white skull corpse. The table below lists the basic details on these grave decoration items.

Preparing the corpses for the graveyard using 3 Important Parts with -2 red skulls/+3 white skulls. The modified parts used in this method are listed in the table above along with the total amount of Sin Shards required for the modifications.

Step 1: Prepare a fresh corpse by removing all the body parts except the bone and skull.


Step 2: Add all the modified body parts but not the Important Parts (Brain, Heart, Intestines) yet. The corpse should now have a total of 12 white skulls and no red skulls.


Step 3: Embalm the corpse with the injections listed below. The resulting corpse after embalming should have 17 white skulls.

1. Dark injection
   
2. Glue injection
   
3. Lye injection
   
4. Silver injection
   
5. Gold injection

Step 4: Now add all 3 of the Important Parts with -2 red skulls/+3 white skulls to the corpse and you should get the 26 white skull corpse.


Step 5: Bury the corpse with the best possible grave decorations i.e Marble sculpture VI and Marble grave fence VIII.

Preparing the corpses for the graveyard using 2 Important Parts with -2 red skulls/+3 white skulls and 1 Important Part with +3 red skulls/+3 white skulls. The modified parts used in this method are listed in the table above along with the total amount of Sin Shards required for the modifications.

Step 1: Prepare a fresh corpse by removing all the body parts except the bone and skull.


Step 2: Add all the modified body parts but not the Important Parts (Brain, Heart, Intestines) yet. The corpse should now have a total of 12 white skulls and no red skulls.


Step 3: Embalm the corpse with the injections listed below. The resulting corpse after embalming should have 17 white skulls.

1. Dark injection
   
2. Glue injection
   
3. Lye injection
   
4. Silver injection
   
5. Gold injection

Step 4: Now add all the Important Parts with -2 red skulls/+3 white skulls and +3 red skulls/+3 white skulls to the corpse and you should get the 26 white skull corpse.


Step 5: Bury the corpse with the best possible grave decorations i.e Marble sculpture VI and Marble grave fence VIII.

With the new Organ Modifications mechanic it is now possible to make a 26 white skull corpses. These 26 white skull corpses can be resurrected into 65% work efficient zombies. Although all the methods listed in this guide will always make 65% work efficient zombies it is better to save 0 red skull/+26 white skulls corpses for the graveyard. The efficiency of these zombies varies with the total amount of white skulls present on them and remains unaffected by any red skulls. A list of efficiencies of the zombies based on the total amount of white skulls it possess are given below.

Preparing the corpses for zombies using 2 Important Parts with +3 red skulls/+3 white skulls and 1 Important Part with -2 red skulls/+3 white skulls. The modified parts used in this method are listed in the table above along with the total amount of Sin Shards required for the modifications.

Step 1: Prepare a fresh corpse by removing all the body parts except the bone and skull.


Step 2: Add all the modified body parts including the Important Parts (Brain, Heart, Intestines). The corpse should now have a total of 21 white skulls and 4 red skulls.



Step 3: Embalm the corpse with the injections listed below. The resulting corpse after embalming should have the required 26 white skulls along with 2 red skulls.

1. Glue injection
   
2. Lye injection
   
3. Silver injection
   
4. Gold injection

Step 4: Resurrect the corpse to get the 65% work efficient zombie.

Preparing the corpses for zombies using 3 Important Parts with +3 red skulls/+3 white skulls. The modified parts used in this method are listed in the table above along with the total amount of Sin Shards required for the modifications.

Step 1: Prepare a fresh corpse by removing all the body parts except the bone and skull.


Step 2: Add all the modified body parts including the Important Parts (Brain, Heart, Intestines). The corpse should now have a total of 21 white skulls and 9 red skulls.



Step 3: Embalm the corpse with the injections listed below. The resulting corpse after embalming should have the required 26 white skulls along with 7 red skulls.

1. Glue injection
   
2. Lye injection
   
3. Silver injection
   
4. Gold injection

Step 4: Resurrect the corpse to get the 65% work efficient zombie.

• Prayer for Souls' thorough Cleansing is quite helpful in making the current best 26 white skull corpses as they provide extra Sin Shards for healing a soul which can be quite useful for modifying body parts.
  
• Silver and Gold injections requires red skull(s) for embalming. So if you don't have any red skulls left on a corpse you can either add a temporary dark organ or embalm it with a dark injection along with removing the skull if necessary.
  
• You can also use modified 0 red skull/+3 white skulls or +2 red skulls/+3 white skulls Important Parts along with two -2 red skulls/+3 white skulls Important Parts to make an all 26 white skull corpse.
  
• Modifying body parts is one of the new feature in the game. The modifications cost a certain amount of Sin Shards for upgrading the quality of red/white skull on almost all the body parts. The cost of modifying these parts are listed in the table below.
  
  Modification Performed

  Sin Shards Consumed

  -2 skulls to -1 skull

  2 shards

  -1 skull to 0 skull

  2 shards

  0 skull to +1 skull

  2 shards

  +1 skull to +2 skulls

  3 shards

  +2 skulls to +3 skulls

  4 shards
• The modifications can only be performed on Blood, Fat, Skin, Flesh and Important Parts (Heart, Brain, Intestines). Skull and Bone cannot be modified as of now. These modifications can only increase the red/white skulls on the corpse and can't remove a skull from them.
  
• Zombie efficiency is only affected by the number of white skulls on a corpse and ignores any red skulls. Therefore, all 4 of the above listed 26 white skull corpses will always be resurrected into a 65% work efficient zombie.
  
• Zombie efficiency does not affect the transportation speed for the zombies. It only decreases the amount of time that it takes for a zombie to craft/farm an item. So, always use your better zombies on the workstations that take the longest time such as alchemy workbench, winery etc.

If you find anything wrong with the information or the pictures that I've provided then please let me know in the comments. Feel to free ask any question(s) that you have regarding the game in the comments below as well.

Edit 1: [31/12/20] No changes in the guide, just wanted to thank everyone for all the awards and support.
Edit 2: [02/11/21] Updated the guide with info on the new 26 white skull corpses and the new dlc content.
Edit 3: [11/11/21] Updated the guide with based on the release of new grave decoration items in patch 1.403.

Final Edit: [10/09/24]

No changes in the process have been made to the original guide, I have just corrected some of the wording withing the guide in order to finalize it for the community. It is clear at this point that the developers have moved on to their next in-line projects, finalizing Graveyard Keeper and its story for now. I would like to thank the community for showing support to my guide and as for the guide, I will continue to support it in case they decide to drop a DLC.