This chapter reviews a number of very rare chromosomal rearrangements: centromere fissions, complementary isochromosomes, telomeric fusions, balancing supernumerary chromosomes, neocentromeres, jumping translocations, and chromothripsis. Centromere fission results when a metacentric or submetacentric chromosome splits at the centromere, giving rise to two stable telocentric products. The Robertsonian fission reverses the fusion that had originally generated it. Telomeric fusion leads to a 45-chromosome count. With the balanced complementary isochromosome carrier, two stable exactly metacentric products are generated. A balancing small supernumerary marker chromosome contains material deleted from the normal homolog. A supernumerary chromosome lacking a normal centromere can become stable and functional due to the generation of a neocentromere. In jumping translocations, a segment can move from one chromosome to two or more recipient chromosomes. Chromothripsis takes complex rearrangement to a yet more complex level. The reproductive risks associated with each are noted.