When called upon to name my most underrated actor, several names came to mind: Don Cheadle, Greg Kinnear, Mark Strong and half the cast of Lost to name but a few. Narrowing it down to one seemed impossible. Why not make it a Top 10 list? Everybody loves those right?

Then it dawned on me.  How underrated can an actor be if his name comes instantly to mind?  My actress is such a chameleon that you remember the characters she creates instead of her persona or even her name. She's the antithesis of such Hollywood scene chewers as Jack Nicholson and Al "Boo-yeah" Pacino, who seemingly play themselves in every movie. While her name may lack the cache of an Angelina Jolie, her superb performances make up for her anonymity.

This actress first came to my attention (or so I mistakenly thought at the time), when she made a seven stint guest appearance on The Office.  Joining an established sitcom is like being the new kid in school.  Both actors and new kids will get accused of stealing, whether it's another actor's scenes or another student's significant other.   It takes a while to win the trust of teachers and fans as well. You can expect sarcastic barbs from the snarky shop teacher and message board vitriol from fans who blame you for their favorite character's diminished role. If you're Ted McGinley, your name even becomes Internet shorthand for show-killer.

Rare is the actor or student who can ingratiate himself into the in-crowd despite missing out on those years of camaraderie and inside jokes.

Amy Ryan is one such thespian.  Her turn as  Holly Flax--the dorky new head of HR at Dunder-Mifflin--was every nerd's wet dream: a beautiful, quirky blonde who did one mean Yoda impersonation.  Her performance won both the respect of Internet cynics like me and that of her co-star and on-screen soul mate Steve Carrell, who used the occasion of the 2009 Emmy Awards to plead for her return.

The first rule of acting is you're only as good as your scene partner. Ms. Ryan proved this truism every week as her brilliant comedic timing elevated the performance of whomever was lucky enough to share the screen with her. While much has already been written about her chemistry with Carrell, I actually preferred her scenes with Brian Baumgartner--who plays Kevin the dimwitted accountant.  By season five, I had grown tired of his shtick. But Ms. Ryan mistaking his slowness for mental retardation added a new comedic dimension to his character.

It's rare to find a new actress this talented so I googled Ms. Ryan.  Judging by her comedic chops, I expected to find a background in The Groundlings or perhaps Second City but in reality Ms. Ryan is a classically trained actress who graduated from New York's High School of Performing Arts. 

Then came the shocker.  I already knew Amy Ryan.  Unbeknownst to me, she had also delivered my favorite performance of 2007, when she played Helene McCready--a white trash, drug-addicted welfare mom in Ben Affleck's Gone Baby Gone. This performance was about as far from the lovable Holly Flax as one could get and earned Ms. Ryan a much deserved Oscar nomination.

As I researched this post, I unearthed yet more hidden performance gems delivered by this chameleon. Remember the prostitute who knew too much from Changeling who showed Angelina Jolie the ropes at the psychiatric ward?  That was Amy Ryan yet again.

 Versatile actress that she is, Ms. Ryan also plays women on the right side of the law as well, most notably Port Authority Officer Beadie Russell on  The Wire.  Her discovery of thirteen corpses in a storage container set the season two plot into motion.

As you can see from the pictures, Ms. Ryan is indistinguishable from one role to the next. While other character actors make you wonder where you've seen their face before, Ms. Ryan's ability to totally transform herself with just a mischievous look and a dimpled grin sets her apart from the competition.  Contrast her with Charlize Theron, who spent hours in the make-up chair, sported prosthetic dentures and fried her hair to transform herself into a serial killer in Monster. Amy Ryan can achieve the same result with just a harrowed look. If that's not great acting, then I don't know what is.