A crossover is the placement of two or more otherwise discrete
fictional characters, settings, or universes into the context of a
single story. They can arise from legal agreements between the
relevant copyright holders, unauthorized efforts by fans or common
corporate ownership.Crossovers often occur in an official capacity in
order for the intellectual property rights holders to reap the
financial reward of combining two or more popular, established
properties. In other cases, the crossover can serve to introduce a new
concept derivative of an older one.Crossovers generally occur between
properties owned by a single holder, but they can, more rarely,
involve properties from different holders, provided that the inherent
legal obstacles can be overcome. They may also involve using
characters that have passed into the public domain with those
concurrently under copyright protection.A crossover story may try to
explain its own reason for the crossover, such as characters being
neighbors (notable examples being the casts from The Golden Girls and
Empty Nest) or meeting via dimensional rift or similar phenomenon (a
common explanation for science fiction properties that have different
owners). Some crossovers are not explained at all. Others are absurd
or simply impossible within the fictional setting, and have to be
ignored by the series' respective continuities. Still, others
intentionally make the relations between two or more fictional
universes confusing, as with The Simpsons and Futurama, where each
show is fiction in the other. Crossover (fiction) Biography, NetWorth, Height, Age, Weight, Family, Married, Son, Daughter