  Monsters lurk within mathematical as well as literary haunts. I propose to
trace some pathways between these two monstrous habitats. I start from Jeffrey
Jerome Cohen's influential account of monster culture and explore how well
mathematical monsters fit each of his seven theses. The mathematical monsters I
discuss are drawn primarily from three distinct but overlapping domains.
Firstly, late nineteenth-century mathematicians made numerous unsettling
discoveries that threatened their understanding of their own discipline and
challenged their intuitions. The great French mathematician Henri Poincar\'e
characterised these anomalies as `monsters', a name that stuck. Secondly, the
twentieth-century philosopher Imre Lakatos composed a seminal work on the
nature of mathematical proof, in which monsters play a conspicuous role.
Lakatos coined such terms as `monster-barring' and `monster-adjusting' to
describe strategies for dealing with entities whose properties seem to falsify
a conjecture. Thirdly, and most recently, mathematicians dubbed the largest of
the sporadic groups `the Monster', because of its vast size and uncanny
properties, and because its existence was suspected long before it could be
confirmed.
