While there were a whole slew of detectives before Columbo, both in print, films and TV, I believe that Columbo was the first that had the persona of your every day man, rather then the sophisticated "know it all"

I really like Monk, too. But I don't think its as good as Columbo. Actually, I feel that the worst of the Columbo's is better than the best of Monk (with 1 or 2 exceptions). The problem with Monk is that the storys aren't as good as Columbo. They have a wonderful, entertaining character, but don't put as much thought into the plots. Most of the "mysteries" are transparent and not nearly as clever as Columbo.
As for all those detectives that have come before, I guess they all owe a debt to the first & original: C. Auguste Dupin created by Edgar Allan Poe.

I think Poe is usually given the honor of being the the creator of the modern (Dupin) detective story; however, there are elements going as far back as the Book of Daniel and even Oedipus Rex.

Love Poe. I try to read his stuff whenever there is a thunderstorm. I do that with King Lear too. It just seems to go together.
Just as with Columbo...I like watching certain episodes during certain seasons and dates. Troubled Waters in the summer. Bye-Bye (etc.) in the fall, because of the scene in the rain. The Conspirators on St. Patrick's day. The Most Crucial Game during football season. A Matter of Honor on Cinco de Mayo.

Don't look now....but I think I have lost my mind!!!!!!!!!!!!!!

Trying to remember if there's a Columbo episode in which either Thanksgiving or Christmas is in the background or mentioned?