Six methods of character formation according to the 说文解字 shuō​wén​jiě​zì, namely pictograms, ideograms, logical aggregates, phono-semantic compounds, phonetic loans, and derivative cognates

Six styles of calligraphy used during the Xin Dynasty, including ancient script, odd script, seal script, clerical script, seal script for stamps, and bird-and-insect script

The first six books of the Old Testament