Supercharge

The soul sphere is a powerup that appears as a floating blue orb with a human face. Picking one up increases the player's health by 100%, up to a maximum of 200%, and the heads-up display says supercharge!.

At one point in Doom's development, it was intended for the player to have a limited number of lives. The soul sphere was said to contain a human soul (hence the name and appearance) and collecting it would award an extra life. That behavior made it resemble the "extra life" orb item from Wolfenstein 3D.

Appearance statistics
The IWADs contain the following numbers of health bonuses: