Character validation systems and methods are implemented. Characters in a data processing system may be may be represented by a set of n-bit data values, however not all n-bit values necessarily represent valid characters. Each data value corresponding to a character of a stream of characters may be validated in response to a member of a data structure corresponding to the value, in which each member of the data structure includes validity information for a corresponding data value. The member may be addressed by indexing into the structure with the data value.