I must posthumously nominate my hen BeBe. She was a tiny mixed-breed bantam, so little that we'd pick her up & joke "where do you put the batteries in?" But she was an outstanding broody, and an excellent attentive Mama after the hatch.
I lost track of how many batches of chicks she hatched out, her own eggs and those of other standard hens. She incubated eggs during our rare Fla freezes, and in all other types of weather. She even once took over for another flighty young hen who sprang off her nest one afternoon mid-set. BeBe was just going broody herself, and I rushed her over to those cooling eggs. She climbed right on them and took over where that other hen quit, and must have been surprised to have that clutch hatch out so soon.
Sadly, she died one night defending her latest chicks from a predator.
She was in a pen with another Mama hen, who chickened out & ran away across the yard. But poor BeBe was found dead next to the remains of her chicks, the feathers off her head, as if the predator was trying to keep her away from fussing at him while he ate the chicks. BeBe, the superior broody, died on the job, while the "chicken" chicken is still alive today.
Rest in peace, BeBe!