In the play, we encounter two ostlers: Robin and Rafe. An ostler is similar to an innkeeper. The ostlers appear in this play for two main purposes. First, they provide comic relief. However, they also have the important task of offering some parallels to Faustus's character. The ostlers are able to learn basic conjuring, just like Faustus. This shows that such tricks are not particularly difficult or enlightened, and encourage the reader to think less of Faustus.
