  Recent rotation measure observations of a dozen or so galaxy clusters have
revealed a surprisingly large amount of magnetic fields, whose estimated energy
and flux are, on average, $\sim 10^{58}$ ergs and $\sim 10^{41}$ G cm$^2$,
respectively. These quantities are so much larger than any coherent sums of
individual galaxies within the cluster that an efficient galactic dynamo is
required. We associate these fields with single AGNs within the cluster and
therefore with all galaxies during their AGN phase. Only the central, massive
black hole (BH) has the necessary binding energy, $\sim 10^{61}$ ergs. Only the
accretion disk during the BH formation has the winding number, $\sim 10^{11}$
turns, necessary to make the gain and magnetic flux. We present a model of the
BH accretion disk dynamo that might create these magnetic fields, where the
helicity of the $\alpha - \Omega$ dynamo is driven by star-disk collisions. The
back reaction of the saturated dynamo forms a force-free field helix that
carries the energy and flux of the dynamo and redistributes them within the
clusters.
