In Robert Louis Stevenson's The Strange Case of Dr. Jekyll and Mr. Hyde, Mr. Richard Enfield only appears briefly, at the opening of the story. He is a distant kinsman of the main narrator, the lawyer, Mr. Utterson, with whom he enjoys a weekly walk every Sunday. On one of these walks, Enfield recounts a story of Mr. Hyde injuring a child and also identifies a house to which Hyde possesses a key.
Enfield is significant because he is an ordinary man, not a lawyer or doctor, and gives us a sense of how ordinary people react to Mr. Hyde. Enfield is not particularly imaginative or credulous, nor abnormally intelligent, but somewhat average, and thus almost stands in for us as readers.
The episode that Enfield recounts serves two purposes in the plot. First, it gives us a sense of the sinister character of Mr. Hyde, and second it gives Mr. Utterson, a man not prone to idle curiosity, a motivation to investigate Dr. Jekyll's strange behavior.
Enfield's reaction to Hyde is particularly interesting:
... the man trampled calmly over the child's body and left her screaming on the ground. ... But there was one curious circumstance. I had taken a loathing to my gentleman at first sight. So had the child's family... [The doctor] was like the rest of us; ... sick and white with the desire to kill him.
This description sets up suspense only resolved when we discover that indeed Hyde is not just an ordinary bad person, but one scientifically engineered to be without moral nature.