Can you determine what the twelve words below have in common?

ALTER
ARK
AVID
DAM
EON
ITCH
LINT
LIVER
RANK
SCAR
TAN
THAN

HINTS:
#1: The title of this puzzle is MISSING INK.
#2: A single letter, appropriately placed in each word, will change the words so that they all have something in common.

Answer:

All the words become common men's names when the appropriate letter is added at the beginning of the word:

WALTER
MARK
DAVID
ADAM
LEON
MITCH
CLINT
OLIVER 
FRANK
OSCAR
STAN
ETHAN 

Credit: GAMES Magazine - Dec. 1994
John Chaneski
MISSING INK