Use large variables without using much memory
The data structure will take 64 bytes as sizeof bool is 1 byte not a bit. The first option is to pack each line (or column) in a byte (or bytes). The prefix 0b is for binary constant value (in gcc). 

uint8_t Char_B[8] = {
0b01111000,
...
0b01111000
};


The second option is to move the data structure to program memory.

const uint8_t Char_B[8] PROGMEM = { ... };


This will require reading each line with a special function.

for (int line = 0; line &lt; sizeof(Char_B); line++) {
  uint8_t pixels = (uint8_t) pgm_read_byte(Char_B + line);
  ...
}