R.J. MacReady is a helicopter pilot for U.S. Outpost 31 in the Antarctic. Part of a twelve man crew, MacReady is the groups outsider. Seldom participating in social activities he takes to playing games of chess quietly in his cabin.
MacReady takes control when the intruder organism infiltrates Outpost 31. It is only towards the end of the film that MacReady truly understands what the intruder organism is capable of and realizes that it may be in the best interests of mankind if no-one survives from Outpost 31.