Pilate is the guy who sentences Jesus to death. Pretty big deal, right? But you might notice that the gospel authors tend to cut him quite a bit of slack. The blame is usually placed on Judas, the blood-thirsty crowd, or the religious authorities—not on the actual person who's ordering the crucifying. Let's take a look.
In the Gospel of John, Pilate decides Jesus's ultimate fate. The religious authorities come to him because they want Jesus put to death but don't have the authority to do it. The trouble is, Pilate can't figure out what Jesus has done wrong. He repeatedly denies that Jesus is guilty of any crime:
Translation: Not guilty.
But don't remove the handcuffs just yet. The Judean court of appeals isn't exactly a model of justice. In the end, Pilate decides that it will be much easier just to crucify Jesus and make the crowd happy. After all, he's just an insignificant Jewish peasant, right?
Basically, Pilate's role in the story is to vouch for Jesus's credibility and to highlight just how low the religious authorities have stooped. But is that what really happened?
Full disclosure: Pilate isn't just a stock literary bad guy. He's also a very real person, who actually served as the Roman governor of Judea from 26 to 36 CE and sentenced Jesus to death (source). And though he comes off as lenient in John's gospel, in reality he was anything but.
Pilate managed to keep rule over the Judean province for ten years, but his relationship with the Jewish people was often strained. The Jewish historian, Josephus, tells us that Pilate repeatedly tried to put Roman emblems in the temple (a violation of Jewish law because they commemorated other gods). That didn't make for very happy subjects.
Another Jewish historian, Philo, wrote that Pilate "was a man of a very inflexible disposition, and very merciless as well as very obstinate" (On the Embassy to Gaius, 38:301). Not exactly a ray of sunshine. He was ultimately removed from Judea by the Roman Emperor after he ordered some powerful Samaritans to be killed.
So would the real Pilate have given a second thought about sentencing Jesus to death? Maybe. If his relationship with the Jewish authorities was hostile, he might have refused to play a part in their little game. It's only because the crowd pushes him so much that he finally caves in. Pilate also seems to be a bit scared of that crowd. When he hears their accusations and chants, "he [becomes] more afraid than ever" (19:8). After all, they outnumber him and his job is to keep the peace. Why not just execute this guy and get it over with? Pilate takes the easy way out.
Pilate definitely gets some choice roles in art and literature: