Often the longer a person’s name, the more we think they might be educated, confident, accomplished or possess many other desirable qualities in a hero or heroine. For example, if you want a strong male character in your novel, will you go with Alexander Wainwright or Tom Smith? If your female character is a sophisticated, well educated, statuesque beauty, will she be known as Elizabeth Castlewood or Susan Jones?
J K Rowling also had these things in mind, when creating the names for both the heroes and villains that inhabit the Harry Potter universe. Professor Severus Snape, for example, is a perfect name for the man who symbolizes Slytherin house. It also seems highly appropriate for a serpentine, snake in the grass kind of person that you will never truly trust, no matter how much faith Dumbledore seems to have in him. Malfoy, according the Rowing, means bad faith in old French. However, this is relatively unimportant, since just the sound of this name is enough to personify an evil or at least highly unlikable character. Names are very important and you only get one chance to make a first impression, so make sure you make the right choice.