What nursery rhyme character wore a night gown?

Answer 1

Wee Willie Winkie ran round the town, upstairs and downstairs in his night gown. Tapping at the windows, crying through the locks, "Are all children in their beds, it's past eight o'clock!"

The wolf in Little Red Riding Hood wore a night gown.

Answer 2

Little Bo Peep is a nursery rhyme character who is often depicted wearing a nightgown.