pandas read a text file and split the names into columns based on the first character

Probably not the best way:

# notice the header=None option
df = pd.read_csv('file.txt', header=None)

# extract the first character of the string
df['start'] = df[0].str[0]

# group by the first character of the string
# cumcount gives you the order/rank of the row within its group
df['idx'] = df.groupby('start').cumcount()

# pivot - search StackOverflow for 47152691
df.pivot(index='idx', columns='start', values=0)

Output:

start       A       B       C       D       E       F
idx                                                  
0      AAAAAA  BBBBBB  CCCCCC  DDDDDD  EEEEEE  FFFFFF
1      AAAAAA  BBBBBB  CCCCCC  DDDDDD  EEEEEE  FFFFFF
2      AAAAAA  BBBBBB  CCCCCC  DDDDDD  EEEEEE  FFFFFF
3      AAAAAA  BBBBBB  CCCCCC  DDDDDD  EEEEEE  FFFFFF
4      AAAAAA  BBBBBB  CCCCCC  DDDDDD  EEEEEE  FFFFFF