Foster's Home for Imaginary Friends (2004)

Eight-year-old Mac has outgrown his imaginary friend, says his mother, so he takes his buddy Bloo (a walking, talking security blanket) to Foster's Home for Imaginary Friends. Here all sorts of odd characters, given up by their creators, are welcome to stay until new kids come to adopt them. Mac strikes a deal with Madame Foster, the proprietor: as long as he comes to visit every day, Bloo will not be put up for adoption.