Person_1     Person_2     Person_3
0   John Smith   Jane Smith   Mark Smith
1   Harry Jones  Mary Jones   Susan Jones

df = pd.DataFrame([['John Smith', 'Jane Smith', 'Mark Smith'],
               ['Harry Jones', 'Mary Jones', 'Susan Jones'],
              columns=['Person_1', 'Person_2', 'Person_3'])

Person_1     Person_2     Person_3
0   John_Smith   Jane_Smith   Mark_Smith
1   Harry_Jones  Mary_Jones   Susan_Jones