gt is a massive franchise and is the closest thing sony ha to a mascot.

All of those IPs are currently owned by Sony except for Crash Bandicoot, and I'm really not sure why it's up there.  That's Wikipedia for ya, I guess. :P

OH yeah, i forgot... these games are terrible....... NOT..!!!!!

Shenmue (AMAZING)
Virtua fighter (The purists choice)
NIGHTS (for its time unique and still unsurpassed)
Streets of rage 2 (Greatest side scrolling beat em up of all time)
Daytona usa (up there with the best)
Sega rally (Best rally game EVER)
Virtua tennis (Best tennis game on the planet)
Jet set radio (Fantastic)
Shinobi series (Memorable)
Virtua cop (took gun games to the next level)

and so on...........

I think you are confusing mascots with flaships.

A mascot refers specifically to a character. Sonic is Sega's mascot. Mario is Nintendo's mascot. Master Chief is Microsoft's. PacMan is Namco, Megaman is Capcom, and Solid Snake Konami.

A flagship title is a game or series of games that the company is best known for. Sometimes these share the name of the mascot (Mario, Sonic, PacMan, MegaMan), sometimes they do not (HALO, Metal Gear), and sometimes they don't even feature a mascot (Grand Tourismo, Final Fantasy). Hell, sometimes the company mascot's series falls from grace, and new flagships come along, but the mascot never goes away (see Sonic, PacMan and MegaMan, who have seen their games supplanted by the likes of Soul Caliber and Resident Evil). Hell, think about Disney and Mickey Mouse. Mick hasn't starred in a flick in ages, and most of Disney's entertainment revenue comes in decidedly non-rodent forms, yet no one thinks Buzz Lightyear or the Little Mermaid when they hear the name "Disney". 

And the last time most of these series were relevent (if ever), a gallon of gas cost less than a large coke at Mickey Ds.

Seriously, as an old school gamer I have respect for Sega, but they have just flushed it all down the crapper since the DC died. 

I have a few:

* Ratchet & Clank
* Jak & Daxter
* Nathan Hale
* Kratos
* Sackboy
* Sly Cooper
* Or, a combination of Singstar, Buzz and Eyetoy games.

I was gonna say Lightning, but we all know what happened to FFXIII...

 The problem is that the mascot has to be instantly associated with the company. When you say "Disney" you think Mickey Mouse. McDonald's is Ronald McD. Marvel Comics is Spider-Man. Nintendo is Mario. On occasion you get two mascots (Batman and Superman for DC, arguably Link for Nintendo), but most of the time there is one who clearly stands out above all the others. None of these have yet stepped up to grab the mantle. As someone said earlier, the fact that there is no immediate concensus means that there just isn't a mascot.

SONY came along and effectively stuck 2 fingers up at SEGA and killed them purely due to sonys financial muscle.... to even suggest that SONY are even half as talented as SEGA is INSANE..... sony BOUGHT their success....... theres a difference between buying your success (SONY) and having actual talent (SEGA) and yes, sega have faltered over the years, but its hardly suprising considering a lot of the staff who worked for sega now have to ply their trade elsewhere......... and that list above of SO CALLED sony MADE games is trebled by SEGA....

If you count sales, then he's got a point.

Every installment of GT has exceeded that of Halo and Zelda and has been on par with or exceeded every installment in the main series of Mario on consoles(excluding SMB and Super Mario World, which were bundled).

That's not the point. tombi just said it was MORE massive than those other franchises. Zelda? Yes. Halo? Arguably. Mario? Don't kid yourself.

Gran Turismo main series:
PS1: ~102 million
GT1: 10.85
GT2: 9.37
PS2: ~120 million and counting
GT3: 14.87
GT4: 9.36

Mario main series: (not counting rereleases)
NES: ~62 million
SMB: 40.24 * significant manufacturer bundling
SMB2: 7.46(A) + 2.65(J) = 10.11
SMB3: 17.28
SNES: ~49 million
SMW: 20.61 * significant manufacturer bundling
SMW2YI: 4.12
N64: ~33 million
SM64: 11.89
GC: ~22 million
SMS: 6.28
Wii: ~29 million and counting
SMG: 6.79

GB: ~119 million
SML: 18.14
SML2: 11.18
SML3: 5.19
DS: ~76 million and counting
NSMB: 15.00

Keep in mind that SM64 (for instance) sold more than GT1, 2, or 4, and on less than a third the userbase. SML, on a similar userbase, blows away the whole GT series. NSMB [edit:  has outsold] GT3 on less than 2/3 the userbase. Expect SMG to do at least as well as GT1, 2, and [edit:  4] once the userbase is similar. SMB2 (WW combined total) matches GT2 and 4 on half the userbase, and SMB3 blows them away and beats GT3.

[edit:  I'm aware of the pitfalls of comparing sales/userbase when the userbase was different at game launch.  If anything that makes SM64 and SML look even more outrageously successful.  And since SMB and SMW are conveniently excluded from comparison, Mario is otherwise short on near-system-launch Mario games.]