Poe Soul

After a Poe is defeated, all that remains of the monster (if anything) is its Poe Soul.

Ocarina of Time and Majora's Mask
In Ocarina of Time and Majora's Mask, a defeated Poe will drop its lamp onto the ground, revealing a Poe Soul encased within it. One of these can be snatched up in an Empty Bottle, but if left untouched for a dozen-or-so seconds, it will disappear. In Ocarina of Time, a trapped soul can be sold to the Poe Collector at the entrance of Hyrule Castle Town for 10 Rupees, or consumed. A consumed soul could either restore a part of Link's health or take away health until he only has a partial Heart Container remaining.

Rarer Big Poes drop more valuable souls the Collector will pay a larger sums for (50 Rupees), but the consumption effects of these souls appear the same. The Big Poes can only be found once Link is an adult and as he is traveling with Epona in Ocarina of Time. After Link defeats these ghosts, he must take their souls to the Poe Collector to receive, in addition to money, a score of 100 points. The Collector promises Link to give him something if 1000 points are earned, so the young hero must hunt 10 Big Poes in total and take the souls of each. The reward is a new Bottle. In Majora's Mask, defeating the Big Poe inside the Ikana Well allows Link to give its captured soul to a Gibdo to proceed.

Twilight Princess
In Twilight Princess, Link can collect Poe Souls to receive various rewards from Jovani. There are 60 Poes in all spread around Hyrule. Poes can only be seen and defeated with Wolf Link's senses, so they cannot be obtained while Link is in his regular, humanoid form. Souls are now stored automatically in any amount on the menu's subscreen, and don't need bottles like they did in Ocarina of Time.

Collecting twenty souls for Jovani will net Link a Bottle of Great Fairy's Tears. With sixty souls Jovani will give Link 200 Rupees whenever he asks. This method of collecting the remains of dead enemies for rewards from cursed individuals is vastly similar to the Skulltula Tokens minigame in Ocarina of Time. There is also a similarity in the Poes in Arbiter's Grounds from Twilight Princess and the Poes from Ocarina of Time considering they too drop their lanterns.