Fit a word into an alphabet grid
Husk, 15 bytes

TṪS`?' €…"AZ"ġ&gt;


Try it online!

Explanation

TṪS`?' €…"AZ"ġ&gt;  Implicit input, e.g. "HELLO"
             ġ&gt;  Split into strictly increasing substrings: x = ["H","EL","LO"]
        …"AZ"    The uppercase alphabet (technically, the string "AZ" rangified).
 Ṫ               Outer product of the alphabet and x
  S`?' €         using this function:
                   Arguments: character, say c = 'L', and string, say s = "EL".
       €           1-based index of c in s, or 0 if not found: 2
  S`?'             If this is truthy, then c, else a space: 'L'
                 This gives, for each letter c of the alphabet,
                 a string of the same length as x,
                 containing c for those substrings that contain c,
                 and a space for others.
T                Transpose, implicitly print separated by newlines.