Think of a character

Barley
Ravenpaw would have no where to go

Jayfeather

The Clans wouldn't exist, nor would the tribes.

Blackstar. ShadowClan is dead.

Sandstorm

I wouldn't have read it.

They're the same cat.

Onewhisker

Mudclaw would be leader of WindClan, and maybe they wouldn't have that stigma surrounding them that they're weak

Or maybe my wish would be fulfilled and Violet and Twig would run away together

Ivypool, guess the dark forest is taking over, rip.

Rainflower. ON one hand, one of the biggest jerks in the series is erased, but on the other hand, Crookedstar's Promise probably wouldn't be as good.

Mapleshade

Everything would be ok. Firestar wouldn't have had to die, and many other cats, including Tigerstar might not have been evil cause maple has always been guiding tigerstar. until he deid forever of course.

But then we wouldn't have the Mapleshade joke threads 

Without a Tigerstar, many things would change. And actually, I wrote an ENTIRE article that's between 2,000-3,000 words on Kate's blog. Anyway, here it is. POSSIBLE SPOILERS AHEAD

In BP, Tigerstar attacked Tiny. Without Tigerpaw,. Tiny won't have been attacked so that means no Scourge and no BloodClan. Redtail would've lived without Tigerstar there to kill him and most likely he'd become Redstar. Ravenpaw also wouldn't have left and so, he'd stay in the Clan. The in the original arc when Firespaw. Bluestar, Tigerclaw, Graypaw and Ravenpaw were at the Moonstone, ThunderClan was attacked and two kits were taken. Without Tigerstar there to reveal the weakness of ThunderClan, ShadowClan wouldn't have attacked so Spottedleaf and Lionheart both would've lived. With Redtail alive still being deputy, Lionheart wouldn't have taken his place. And, Yellowfang would've been an elder considering Spottedleaf is still alive then too. Also, that would've meant Brtokenstar would've never attacked ThunderClan in the first place. And in turn, Graypaw and Firepaw would have to wait to get their names. With Spottedleaf alive, Firestar and her would've become mates or find out their "love" for each other and stayed friends. Without Tigerstar, Goldenflower wouldn't have given birth To Tawnypelt or Bramblestar.
There would've been no trap on the Thunderpath for Bluestar, so Cinderpelt would've never had been crippled. She also wouldn't have the bond with Yellowfang like she did and probably would've gotten a mate. Perhaps in Runningwind or Swiftpaw. Both Runningwind and Whitethroat would also be alive without Tigerstar there. At some point, ShadowClan would probably be dealt with in terms of Brokenstar.

After he was gone, Nightpelt would probably be dead at that point, so who knows who would be leader. Maybe Blackfoot and Russetfur as well as other members were accepted into the Clan at some point. Anyway, knowing Bluestar, WindClan might've been brought back, however much later than in the books. There'd most likely be no attack from the rouges in FoS, so Bluestar would've never have been cornered by Tigerstar and thus, not have gone crazy. With her mind in a good state, all the apprentices would've gotten their names on time. So, there'd be no reason for Swiftpaw and Brightheart to prove themselves. On top of that, due to there not ever being any dogs, Brindleface and Swiftpaw would've lived and Brightheart wouldn't have been disfigured. And I firmly believe that she and Cloudtail would've still become mates because Swiftpaw and Brightheart seemed more like friends.

Though the ThunderClan leader sacrificed herself, she was very old so I believe she would've died of old age and thus, Redtail would've become Redstar. Fireheart probably would've become deputy or maybe he would've made his daughter Sandstorm become it. Speaking of those two, I still believe they would've become mates with Fireheart proving himself to the Clan. Without Tawnykit or Bramblekit, Darkstripe wouldn't have brought them to Tigerstar. And if he wasn't visiting Tigerstar, he would've never fed deathberries to Sorrelkit and might actually have been good. He also wouldn't have joined TigerClan and later BloodClan. Speaking of which, Stonefur would still have lived to be RiverClan's deputy and possible leader. Sasha wouldn't have met tigerstar and possibly either die in the streets or got picked up. And with those two becoming mates, there'd be no Mothwing, Hawkfrost or Tadpole. When the time for the final battle came, no one would've died. At some point, Redstar would either die or retire and we'd get either a Firestar or Sandstar.



On to The New Prophecy, already there'd be no Tawnypelt or Brambleclaw, so other warriors would go in their place. Perhaps Squirrelflight or Leafpool and another ShadowClan cat. As I mentioned before, there'd most likely be no Russetfur or Blackstar and if they were accepted back into the Clan, they'd most likely not hold any high ranks. After the journey, Ashfur and Squirrelflight would've stayed friends and there'd be no Brambleclaw-Squirrelflight-Ashfur drama. Perhaps Squirrelflight and Ashfur would've become mates, Squirrelflight would've stayed single or she'd get a different mate. As for different mates, I can see her being with either Sootfur or Rainwhisker andlet's face it; if either of them were her mate, they wouldn't have died. When Berrykit got his tail stuck in the fox trap, perhaps ShadowClan would've helped him. With Hawkfrost non-existent, Brambleclaw and Squirrelflight would never have argued, or let alone have a relationship considering there'd be no Tigerstar. And with no Hawkfrost, Ashfur would've never have been planning with the RiverClan tom so Firestar or even Sandstar wouldn't have gotten captured in the fox trap.



Onto the Power of Three, Squirrelflight might've been mates with Sootfur or Rainwhisker so the three could still be hidden. Another possibility is Squirrelflight would've remained single so she'd either have to make up a story about the three's father or Leafpool would've had to come clean with her kits. If Leafpool took came clean, Jay, Holly and Lion would've been mistrusted due to their father being from WindClan. If that were the case in which Leafpool had to take care of the three, Brightheart most likely would've temporarily taken over for her. If Squirrelflight did take either Sootfur or Rainwhisker as her mate, everything with Holly, Jay and Lion would've remained the same up until the secret was revealed. I still believe Ashfur would've been jealous and things probably would've remained the same for him. To add, Lionpaw would've never been visited by Tigerstar in the first place, thus never seeing visions of him killing Heathertail. Focusing on Tigerstar's family in ShadowClan, there would be no Dawnpelt, Tigerheart or Flametail because Rowanclaw and Tawnypelt wouldn't have become mates. More will be added on this later.

Now, as for the biggest thing in this arc was the reveal that Jayfeather, Hollyleaf and Lionblaze weren't the kits of Squirrelflight and Brambleclaw. I believe things would've gone down differently. If Sootfur was the mate of Squirrelflight when the secret was reveled by Hollyleaf, he most likely would've been angry at first. During that time, he and Squirrelflight may drift a part, though I believe he would've forgiven her in the first few books of OotS, unlike Bram,bleclaw, they both would stay as mates. If she and Rainwhisker were mates during this time, I don't think Rainwhisker would be angry, but hurt. He'd quickly forgive his mate and understand why she did what she did.



Moving onto the last arc, in the first book there is a drought. During the drought, Dovepaw hears beavers and the Clans go on a journey to stop them. Tigerheart goes with them. Without Tigerstar, there'd be no Tigerheart so a different ShadowClan warrior would go on the journey with her and the other warriors. Now without Hawkfrost being there to tempt Ivypaw to join the Dark Forest, she would still be jealous of Dovepaw. Perhaps another warrior would bring Ivypaw to the DF or maybe she'd hold in her anger and jealously of Dovepaw as the arc progressed. If Ivypaw was in the DF, she probably would've ended up spying for the three still. If not, then the three would've been blinded as to what the DF was doing. Now, without Tawnypelt existing, Flametail wouldn't have died and Dawnpelt wouldn't have accused Jayfeather of killing her brother. Thus, there'd be no need for him to be demoted for a little while.

Throughout the entirety of the OotS arc, Tigerstar was one of the major driving forces for the DF and their cause. Without them there, the DF warriors most likely would be less passionate and maybe not even interested in destroying/taking over the Clans.
During Fading Echoes/Night Whispers when Ivypool is taken by ShadowClan, Tigerheart wouldn't force her to be traded for herbs he didn't know about because he and Dovepaw wouldn't be meeting. And if Dovepaw and Tigerheart wouldn't meet, there'd be no stupid drama between Dove-Tiger-Bumble. This would mean, Bumlestripe and Dovewing would probably end up being mates. When Jayfeather visits StarClan in The Last Hope, Flametail almost let's him die in StarClan. Actually, how does that even work, dying in StarClan? Anyway, Jayfeather would have no need to look for him so he would never even come close to dying. Without much passion from the DF, they would either no attack the Clans, or quickly loose the battle. And if there is no battle, none of the warriors like Foxleap, Sorreltail or Ferncloud would've died.

SPOILERS AHEAD FOR TAQ AND TAS! DON'T READ IF YOU DO'T WANT SPOILERS! YOU HAVE BEEN WARNED!


I haven't read the new arc nor do I intend to, however, from what I've heard, I'll try and make an accurate prediction.

For TAQ, if Squirrelflight had kits with either Sootfur or Rainwhisker, then we'd get Alderpaw and Sparkpaw, but most likely with different descriptions. Now if she never took on a mate, we'd most likely see one of or all of Lionblaze's kits in their spot.

As for TaS, Sleekwhisker and Juniperclaw, the kits of Dawnpelt, wouldn't be the main driving forces for the rebellion of the ShadowClan apprentices. This would be due to them not being born.