In Warhammer 40,000, "
Apothecary" is the title given to the Space Marine whose job it is to treat the wounded and collect the geneseed from his fallen brothers. They are fully fledged members of the Space Marine Chapter and actively participate in combat. They frequently wear white Power Armor and carry fewer weapons but they get other things to balance that out.
As far as gameplay is concerned, their stats are usually close to the generic Space Marine but, they have some special wargear and abilities that make them a valuable member of the team.
In game terms, this means that the normal apothecary can do two very useful things. The first is that any squad they are attatched to can neglect the first failed armor save, meaning the hit model is not removed from play. The second is their ability to remove the geneseed, which allows the player to get victory points for fallen soldiers. While this may not sound like a big deal, at the end of the day it is the VPs that are used to determine victory.
They also made an appearance in SSI's computer game Chaos Gate, where they even get to carry bolt pistols. When a weapon finally broke through a soldier's armor, he could occasionally be heard to shout, "
Apothecary! I am wounded!"