Care to list you ultimate 'you must see this' list?

[Sukunai]

We've all pretty much established we are all not just casual anime watchers.
You're a fan just for being here in the first place.
Fanatic might apply if do moire than just settle for watching anime though.

So that all said, what would you list as your 'you must have watched this series' not limiting yourself by genre in any fashion ie if it's anime, it's in the running.

This isn't a top ten listing or even a top 100 listing. It's not about sales figures or age of the anime either.

My list would begin with

Sailormoon
Ranma
Urusei Yatsura
Slayers
Tenchi Muyo

These were the ones that got the ball rolling for me, that opened the flood gates.
I watched a lot of anime in between all of those in bits and pieces, but these are the shows that made me interested in all the rest.
I guess I have been into anime since like 95.

[The Origonal Head Hunter]

Outlaw Star
Cowboy Bebop
Rurouni Kenshin
Dragon Ball Z
Lupin the 3rd

These, aside from the saturday morning stuff, were my introduction into anime. Let's face it, the old school toonami run was full of the must-see stuff that made a lot of fans.

And others that are must-sees:
Gungrave
Black Lagoon
His and Her Circumstances
5 Centimeters Per Second
Haibane Renmei

[Ishbalan]

Bottle Fairy

[Kariudo]

Great story, great storytelling. This is the stuff that drew me in and kept me hanging week after week.
Code Geass (R2 as well)
EF- a tale of memories and a tale of melodies
Gundam 00 (S2 as well)
Clannad

The classics, the first 3 are what really got me into anime. Toonami had some good stuff, but [as] gets most of the credit here.
Trigun
Lupin the 3rd
Cowboy Bebop
Outlaw Star

The funny/WTF. Everyone needs a good laugh
FLCL
Dead Leaves
Pani Poni Dash
Full Metal Panic! Fumoffu

Misc. just some good stuff that was entertaining.
GitS SAC (and 2nd Gig)
Eva (classic, yes. But I hated the ending, both of them)
Last Exile
Death Note
.Hack//Sign (I liked Roots too)

[Ishbalan]

Boku no Pico

[Chiikaboom]

Cardcaptor Sakura & Kodomo No Omocha.

[Vivaldi]

Boku no Pico

ಠ_ಠ

[Ishbalan]

Tokyo Tribe 2

[Immorrel]

Well the first anime I watched that I knew was anime and actually got me started was Armitage: Polymatrix and Macross Plus, but previous to that is all the stuff that I used to watch that I never knew was anime until after I did my research. For example

Teknoman (Tekkaman Blade)
Thundercats
Voltron

And I agree with Headhunter, the old school Toonami shows should be on anyone's list since most all of it is iconic.

[Sukunai]

While not numbered among my earlier animes

Azumanga Daioh and Pani Poni Dash are easily likable animes for being just so much silly fun and not really having any downside (in my view).

Noir and Madlax I consider great 'serious drama' animes.
I prefer BGC 2040 over the earlier form. I guess I like the artwork of 2040 more.

Air TV was the first anime to pry money out of me though. Paid an obscene seeming sum of money for it.
Clannad with Afterstory is rapidly becoming an equal of Air TV for me.

But I guess my first truly liked romance anime series was Ah My Goddess. I was so happy to get two more seasons of it.

I like a few of the scifi looking series lioke Blue Gender, but I can be fussy on them.