This review article covers the development of Fischer carbene complexes since the year 2000, with specific
focus on carbene complexes bearing metal-containing fragments as substituents, as well as multicarbene
systems. The role of the metal-containing substituents on the character and reactivity of such complexes
are discussed. In addition, larger systems containing more than one carbene ligand are also covered (rodlike
biscarbenes, chelates, macrosystems, etc.) in terms of the synthesis, reactivity and structural aspects.