Which champion is forced to build 1 item/to follow one build path?
Yesterday I was playing Sett and looked him up on onetricks to find out which runes and build to use. To my (mild) surprise, literally every Sett main in high elo goes Stridebreaker, and there is basically zero variety in the next two items. Most go Stride > Cleaver > Bloodmail, with a few going Bloodmail > Steraks or Cleaver > Steraks instead after Stride.
This was surprising even though I knew Stridebreaker is Sett's main item, because most other champions still have some build variety, even if it's gimmicky and flat out worse than their usual core items.
This raised a question, which champion is the most "forced" into a single build path?
Irelia
Irelia was the first champion I thought of. Her kit works so well with Blade of the Ruined King that it's what everybody builds. AP Irelia has recently become a thing-ish thanks to Baus, and I found an Irelia main who goes AP. It seems to have enough gimmicky moments that it isn't a full troll build, but I'd say she's still up there for being bound to BotRK. However, build variety after BotRK is pretty good, with many different paths, so she may not be #1 on this list.
Ezreal
The other champion I thought of was Ezreal. He goes basically the same first three items every game (Trinity > Manamune > Shojin), but I found a fair share of players going Essence Reaver instead, and a lot going Endless Hunger instead of Shojin as the third item. There was also one AP Ezreal Challenger player.
I tried thinking of ADCs but with with the items introduced at the start of this season I feel like every ADC I can think of can go a few different build paths, but I guess they are bound to IE/LDR if you'd count that.
So my question is, what are the champions who are most bound to 1 item and build path and are basically never able to go something else?