One of the villains in the classic musical "Annie," Agatha Hannigan is the supervisor of the orphanage in which the title character begins the story. A cruel, uncaring bully and a petty criminal to boot, Miss Hannigan is a thoroughly dislikeable character -- and therefore an ideal costume for Halloween or a similar fancy dress event. Creating a Miss Hannigan costume is less a matter of replicating a specific outfit and more a question of capturing a particular worn and sleazy look.
Dye your hair red (if it isn't red already) and curl it. Miss Hannigan's dishevelled curly red hair is her signature feature. Gather it up loosely but be careful to let some of it fall out; the look you're aiming for is that of an unsuccessful attempt at glamour.
Assemble a 1930s outfit. Miss Hannigan changes costume several times during the film and has also had a range of different costumes on Broadway; she doesn't have a single, identifiable outfit in the same way that Annie does. This is good news for costume purposes: all you need is something that fits the period and the character. Miss Hannigan's clothes should always be a mix of slinky and frumpy. The character sees herself as stylish but is actually harried and ragged.
Pile on the cheap costume jewellery, the tackier the better. In the 1982 film, Miss Hannigan wears a lot of odd jewellery, including bracelets in odd places such as her upper arm. She even wears it to bed.
Overdo your makeup. Bright red lips and deeply shadowed eyes against a pale face will help heighten the impression of bungled beautification.
Accessorise with a flask full of bathtub gin. Miss Hannigan should always be seen with a drink in hand.
If you can get a shorter friend to dress up as Annie, it will go a long way toward making the reference clear to non-fans.