Like dictionaries for the whole Bible, New Testament dictionaries focus on providing (usually lengthy) descriptions of people, places, and things in the New Testament. Some focus on a specific portion of the New Testament, such as the letters of Paul. Others are concerned with the meaning and significance of some New Testament Greek words. These dictionaries can be very helpful for general understanding of a topic and/or for getting good bibliography. However, these dictionaries are not exhaustive. They do not cover every Greek word in the Greek New Testament or every possible subject.
Dicitonary of Jesus and the Gospels by 
Dictionary of Paul and His Letters by 
Dictionary of the Later New Testament and Its Developments by 
The Westminster Dictionary of New Testament and Early Christian Literature and Rhetoric by The resources listed in this area are not on the New Testament specifically but provide information about the world of the New Testament, particularly the Classical period and the Greco-Roman world. These are most relevant for looking up people or subjects that mignt not be in a dictionary on the New Testament.
Dictionary of New Testament Background by 
The World of the New Testament by 
The Eerdmans Dictionary of Early Judaism by 
Encyclopaedia of the Ancient World by 
Oxford Encyclopedia of Ancient Greece and Rome by 
Ancient Texts for New Testament Studies by Unlike the dictionaries on the left, theological dictionaries are focused on specific Greek words rather than topics. Typically a theological dictionary will talk about the meaning of a word over time (diachronic analysis) and its use in the New Testament and other literature of the same time period (synchronic analysis). When you cite an article from a topic-related dictionary or a theological dictionary, you need to cite both the author and the editor.
Theological Lexicon of the New Testament by 
Theological Dictionary of the New Testament by 
Exegetical Dictionary of the New Testament by