The Cromwell Association Online Directory of Parliamentarian Army Officers

http://www.british-history.ac.uk/no-series/cromwell-army-officers contains the names of over 4,000 officers who served in the armies of Parliament during the first English civil war (1642-6), and in some cases subsequently. This alphabetical directory covers all regions of England and Wales and, while not claiming to be comprehensive, brings together in one place the largest listing of parliamentarian officers in service prior to the creation of the New Model Army in 1645.