What is a 'Zombie'?A poker player who is referred to as a zombie is one who essentially gives nothing away in the process of the game. Most players have tells of some kind - subconscious actions, tics, movements and motions which give away something about their hand or their gameplay - but a zombie is able to remain completely emotionless, and with a perfect poker face.
This is an extremely useful skill, and yet it is extremely rare to come across a true zombie in actual gameplay. Most players will react in some way or another to the cards that they are dealt, or as the flop comes up on the table and they make their full house, Aces full of Kings, and actually some who are considered a zombie are actually more likely to just have never played cards with someone who is astute enough to observe their subconscious tells.It is very difficult not to react when making a monster hand, or when you do not make a hand and then resolve to bluff it anyway, and actually in attempting not to react many players overcompensate and make a visibly conscious decision to react as a zombie would, thus giving themselves away anyway.Even players who are not well versed in reading people, observing and testing opponents' tells, and interpreting actions will still subconsciously read and interpret their opponents' body language really quite accurately, and this constitutes what is usually misrepresented as "intuition". So if most players give something away, and most players can read their peers more effectively than they think, then a zombie is a rare breed indeed.