System AdminOnly needed if you are planning on hosting data internally. If using cloud then you can do without.
DBAOnce you have system set up with the right hardware etc, you will need a DBA for curating the data and be the go-to person for the other teams. DBAs play a big role in integration of different sources.
Big Data EngineerThis is the pivotal role and most of the heavy lifting will be done by this role. This person must have good programming skills with some prior data design experience. Desire to learn and good attitude are a must. Things will get frustrating quickly.
AnalyticsWithout having analytics and data science skills in your organization there is not much you can get out of your big data efforts.
VisualizationThis will have major impact on how the executives view your project. Nothing soothes nervous nerves like a good infographic, pie chart that can be put in front of a prospect or a customer.
SecurityThis appears to be a nice-to-have. But resist any urge to make it so. You may not have a security expert but do assign this responsibility to another role and provide time and resources to make this happen.
The list is based on my experience and the data life cycle stages.