  Cosmic voids have been shown to be an effective probe of cosmology,
complementary to galaxy clusters. In this work, we present a simple theoretical
framework for predicting of the size of the largest voids expected within a
given redshift and volume. Our model is based on the exact extreme-value
statistics which has previously been successfully applied to massive galaxy
clusters. We implement our formalism using the void-abundance models and
compare the extreme-void predictions to simulations and observations. We find
that the simplest void models can only explain the extreme-void abundance with
ad hoc parameter adjustments. We argue that extreme-void distributions should
be used as an additional test on theories of void abundance.
