I've seen formulas that can extract unique values from a row or column, like
{=IFERROR(INDEX($B$3:$B$15, MATCH(0,COUNTIF($D$2:D2, $B$3:$B$15), 0)),"")}
but I can't make this work for a range of cells, like this:
<tbody>
A
B
C
D
E
F
G
H
I
J
K
L
M
N
1
Bob
Alice
David
2
Mark
Alice...