I vote for Ransom for a Dead Man. Leslie was a total b-i-t-c-h. Self-serving, arrogant, and generally F'd up. Cared only about money and herself. Really did a number on her step-daughter, although in the end, the step-daughter prevailed.

The most arrogant is difficult to choose. Bart Kepple of "Double Exposure" is up there, especially how he toys with Columbo after being informed of the second murder and in that interesting scene on the golf course.

Have to agree with Leslie Williams in "Ransom
for a Dead Man"---a seductive, yet poisonous
character. Her husband gives up his career
as a State Supreme Court Justice, sets her up
in a flourishing law practice and a beautiful
house in Beverly Hills. With all that, she tells
him to take a hike, YET even after that (and
his threat expressed to his daugther to break
relations with Leslie) he still maintains
a civil relationship with her. His reward is
to be murdered without a hint of remorse on her
part. One thing that surprises me is that she
did rub out the stepdaughter when she started
harassing her.