A fighter win a UFC belt and retire undefeated? Cejudo is the only one that seems on track for it. And Holly Holm has a very realistic chance in just a few more fights. Trilogy with RR and retire off that (beat her three times, the rematch HH wins and then RR smashes all the other girls and then actually earns her rematch only to lose to HH again).
Anyone else? 
Bones Jones
Yeah outside of Khabib possibly (he could earn a title shot then be forced into early retirement from more injuries after defending the belt sporadically), I don't know who else is out there still undefeated.
In a lot of ways, I consider GSP undefeated because he avenged both his losses. He also faced a murderer's row of welterweights.
Bones is a possibility if you don't include his "loss." I think his lifestyle and ego catches up to him eventually, though, albeit maybe not for several years to come.
Holm is a very realistic possibility, but no one would consider her weight class very deep.
I think it would have to be someone that retired early, long before they finally got caught. Otherwise, everyone gets caught.
The above is why I respect GSP so much.
DWRay,
that's not what undefeated means, (the GSP point).
Undefeated means no one was able to figure you out and defeat you. In GSP's case, One man made him tap out to strikes, another made him cry uncle to an arm bar. Two very definitive ways to lose. A guy like Hendricks could make a good case for GSP not having defeated him. GSP can't say the same about Serra or Hughes. We all watched it go down. He surrendered twice.
Bones could argue it wasn't anything the opponent did, in order to caus ehis defeat, and there is a good arguemnt to be made there. GSP cna't make that argument.
That said, Makhov might have a shot at it.
StrikingMMA - Bones JonesYeah that whole loss was/is crazy. 12-6 elbows are illegal bc early commissioners saw videos of karate dudes breaking cinder blocks that way per big John McCarthy haha
Damn... Dana would shit himself.
StrikingMMA - Bones JonesThat's an unfortunate one but that still counts as a loss. Unfair as it is. I'm talking about a fighter with a record of "??-0-0".
DWray - In a lot of ways, I consider GSP undefeated because he avenged both his losses. He also faced a murderer's row of welterweights.Undefeated means never being beaten in a fight. GSP has lost fights. He is still one of the GOAT though, but he was defeated.
Bones is a possibility if you don't include his "loss." I think his lifestyle and ego catches up to him eventually, though, albeit maybe not for several years to come.
Holm is a very realistic possibility, but no one would consider her weight class very deep.
I think it would have to be someone that retired early, long before they finally got caught. Otherwise, everyone gets caught.
The above is why I respect GSP so much.
Holm.
Chadderz -StrikingMMA - Bones JonesThat's an unfortunate one but that still counts as a loss. Unfair as it is. I'm talking about a fighter with a record of "??-0-0".
I have to disagree on the fairness aspect. You should absolutely be disqualified if you repeatedly land illegal strikes and your opponent is bloodied, busted open, and cannot continue. There is no way to excuse those things. He should probably have 2 losses, including the one to Chael, where he badly broke his toe, but the bout ended before it could be discovered.
SinCityHustler -There was nothing wrong with the Chael stoppage imo. He won it inside the round.Chadderz -StrikingMMA - Bones JonesThat's an unfortunate one but that still counts as a loss. Unfair as it is. I'm talking about a fighter with a record of "??-0-0".
I have to disagree on the fairness aspect. You should absolutely be disqualified if you repeatedly land illegal strikes and your opponent is bloodied, busted open, and cannot continue. There is no way to excuse those things. He should probably have 2 losses, including the one to Chael, where he badly broke his toe, but the bout ended before it could be discovered.
Chadderz -SinCityHustler -There was nothing wrong with the Chael stoppage imo. He won it inside the round.Chadderz -StrikingMMA - Bones JonesThat's an unfortunate one but that still counts as a loss. Unfair as it is. I'm talking about a fighter with a record of "??-0-0".
I have to disagree on the fairness aspect. You should absolutely be disqualified if you repeatedly land illegal strikes and your opponent is bloodied, busted open, and cannot continue. There is no way to excuse those things. He should probably have 2 losses, including the one to Chael, where he badly broke his toe, but the bout ended before it could be discovered.
so his toe broke itself after the fight is what youre saying?
Chadderz -SinCityHustler -There was nothing wrong with the Chael stoppage imo. He won it inside the round.Chadderz -StrikingMMA - Bones JonesThat's an unfortunate one but that still counts as a loss. Unfair as it is. I'm talking about a fighter with a record of "??-0-0".
I have to disagree on the fairness aspect. You should absolutely be disqualified if you repeatedly land illegal strikes and your opponent is bloodied, busted open, and cannot continue. There is no way to excuse those things. He should probably have 2 losses, including the one to Chael, where he badly broke his toe, but the bout ended before it could be discovered.
No, the stoppage was good. Had Jones not got the stop, however, the doctor would not have been likely to allow Johns to continue with the broke toe. Given the injury, he is very fortunate to have gotten out of there with his title and without a TKO loss.
Khabib has a good chance of doing it too
Fedoral Crime - Khabib has a good chance of doing it tooYeah that's another good shout.
melancoholic -Chadderz -SinCityHustler -There was nothing wrong with the Chael stoppage imo. He won it inside the round.Chadderz -StrikingMMA - Bones JonesThat's an unfortunate one but that still counts as a loss. Unfair as it is. I'm talking about a fighter with a record of "??-0-0".
I have to disagree on the fairness aspect. You should absolutely be disqualified if you repeatedly land illegal strikes and your opponent is bloodied, busted open, and cannot continue. There is no way to excuse those things. He should probably have 2 losses, including the one to Chael, where he badly broke his toe, but the bout ended before it could be discovered.
so his toe broke itself after the fight is what youre saying?
Legit lol