Many characters in Arthur Miller's The Crucible have a fierce desire for power, though not all of them are looking for power in the traditional sense.
The Reverend Parris is thoroughly obsessed with maintaining power because he is a coward. Before the incident with the girls in the forest, we know that he was consistently preaching hellfire and brimstone, demanding more money and things (such as fancy candlesticks), and generally acting as if he deserved more, All of these things are a play for power and control over the very people over whom he was supposed to be a shepherd.
Once the witchcraft talk begins, Parris is deathly afraid people will blame him and then will remove him from his position. Everything he does from the time the play begins, then, is part of a desperate attempt to keep his position. He does this by deflecting blame onto others, feeding suspicions and doubts, and outright lying.
Another person desperate for power in this play is Abigail. For her, the power she wields over the girls and the court is all for one goal: to get John Proctor back. She lies, she gets others to lie, and she threatens, all in an attempt to achieve her goal. The fact that her actions have life-and-death consequences for others does not ever seem to register with her; all she selfishly cares about is what she wants and how best to get it.
Finally, the judges are quite concerned about power; Danforth, especially, is motivated by his desire to maintain the standing and authority of his court. Note his speech in act four of the play:
Now hear me, and beguile yourselves no more. I will not receive a single plea for pardon or postponement. Them that will not confess will hang. Twelve are already executed; the names of these seven are given out, and the village expects to see them die this morning. Postponement now speaks a floundering on my part; reprieve or pardon must cast doubt upon the guilt of them that died till now. While I speak God's law, I will not crack its voice with whimpering. If retaliation is your fear, know this--I should hang ten thousand that dares to rise against the law, and an ocean of salt tears could not melt the resolution of the statutes.
This is a man who believes he is God's chosen judge but is also consumed with his own legacy in these proceedings. He may not want to make God's voice sound like whimpering, but he is surely just as interested in making sure no one can call him weak.
All of these descriptions fit, at least in parts, the primary players in McCarthyism. Though they claimed to have a righteous cause, many of them were simply trying to deflect attention from their own lives or to destroy other people's lives when they had the power to do so. Miller's point, of course, is that the witch trials were not a one-time occurrence but a reflection of the human condition which has not changed in more than three hundred years.
Abigail Williams – While a servant in John Proctor's household, Abigail briefly became John's lover before Elizabeth found out and fired her. Abigail is crafty, and vindictive. She's also a skillful liar. She wanted Goody Putnam to be convicted so that she could finally have John Proctor all to herself.
Thomas Putnam – One of the richest farmers and landowners in Salem. He is a bitter man who feels that the citizens of Salem have not given him the respect that he and his family deserve. He seeks to gain respect and revenge by increasing his wealth and influence however he can.
Ann Putnam – Mrs. Putnam is as bitter as her husband, but for different reasons: just one of the many babies she has given birth to has survived past infancy.
These characters are just like Americans that fell victim to the Red Scare during McCarthyism. They saw someone successful and labeled them as a Communist. This would undoubtedly ruin their career and soil their image.
Thanks for the great answers!