CharacterRange

CharacterRange["c1", "c2"] yields a list of the characters in the range from c1 to c2.

CharacterRange[n1, n2] yields a list of the characters with character codes in the range n1 to n2.

Examples

Range of uppercase letters:

CharacterRange["A", "Z"]
(* {"A", "B", "C", ..., "Z"} *)

Range using character codes:

CharacterRange[97, 102]
(* {"a", "b", "c", "d", "e", "f"} *)

Please visit the official Wolfram Language Reference for more details.