Actually they weren't grandmasters because the title wasn't officially awarded by FIDE until 1950
The shortest game in history - Guiness record

Guiness Records are full of pointless entries. Some are irksome: the longest fingernails etc. The record game here is also pointless. When a record is so easy to achieve, what 's the point ? A more meaningful example is the longest winning streak etc.
Thats Macer75. 105
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White resigned as he had to either lose his queen or allow checkmate. Notice in the position that white's queen is trapped, it has no square to go to as white's other pieces block those squares. (the knight on d2 plays a critical role in this). Black has only one option to get rid of the knight, with fxe3. However, after fxe3, black plays Queen h4 check, which is a forced mate after g3 and Queen takes g3. If white does not take the knight he will lose his queen, as shown in the lines on the board.
kes g3.
Imagine being defeated by a fellow grandmaster in 4 moves!