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%.

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.

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