What is the total number of films in the "Thin Man" movie series?

The first three feature scripts written by husband and wife team, Albert Hackett and Frances Goodrich. Hackett and Goodrich were one of the greatest pair of screenwriters in Hollywood history. The Thin Man movies featured a new style of banter between husband and wife and character dialog. Other films written by them include, It’s A Wonderful Life, The Diary of Anne Frank, Easter Parade, Father of the Bride, and Seven Brides for Seven Brothers.