In the twentieth century, experimental psychological shifted from the study of the mentally ill to research on the cognitive and personality development of basically normal people. Soon there was a plethora of theoretical models on the formation of personality and creativity, with seemingly different ways of rating personality. But there was some overlap, in fact a lot. In 1961, Ernest Tupes and Raymond Christal sorted through the major theories to see what factors were used repeatedly and settle on five of these named surgency, agreeableness, dependability, emotional stability, and culture. 
This model has been tweaked frequently and the factors renamed; they are typically referred to as Extroversion, Agreeableness, Conscientiousness, Neuroticism and Openness to Experience.  But the theoretical model was only the beginning. Other psychologists developed questionnaires to test for these factors, and performed research to determine the norms , where the average for a population lies.
According to a recent study conducted by Southern Methodist University in Texas, creative ability and creative accomplishments are higher for people with higher scores in Openness to Experience and Extroversion, and lower for people scoring higher in Agreeableness. So it would seem that you can identify creative people because they enjoy a greater variety of things and are more outgoing, but not necessarily as nice as the average person. But it isn’t always that simple. First, you need to know research was based on 75 subjects in Texas universities. Also, creative ability was based on a test measuring verbal creativeness, and creative accomplishments were self-reported.  Creativity shown by personality assessments depends on population being tested and the criteria for being labeled creative. Would extraversion still have a positive correlation with creativity if ability had been measured by visual creativity rather than verbal, or achievement judged by peers rather than self-reported?
Recently I took the Five Factor Model test on a website, attempting to gather data from a population. My scores on the Five Factor Model have remained fairly stable for decades. When I was compared to other people taking the same test (rather than existing norms) I discovered that I had suddenly become much more extroverted and agreeable and a lot less neurotic. I was now comparing myself to average person who takes psychometric tests on the Internet, not the more intentionally random groups selected across the United States. I should not be surprised; my children did warn me that introverts tend to hang out on the Internet.