We all know about those Trynds that try to spin into the middle of us and wreak havoc.
Yeah, the ones that die really fast and don't really bother us.

This comes from being underfarmed and underleveled. From being denied it.
There are several ways to counter his "OMG HIT 700 CRIT WTF" stage. For example, you could perhaps build armor besides the normal Zhonya's Hourglass or Wriggles. I oft see only those items as counter on three's, but in reality, you should have your jungler or a bruiser top build a Frozen Heart or Randuin's Omen. They slow down Tryndamere's DPS ridiculously.
You could also play a counter in ranked, such as Pantheon. When I used AP runes and masteries on accident, and Tryndamere had proper runes, I could still win early fights.

Teemo with ignite + exhaust.

Build MBR, Frozen Mallet, Frozen Heart and enjoy trolling trynd.

Just be sure to blind, then ignite when blind wears off, igniting just before his ult finishes.

Place shrooms on his escape/engage points (dragon wall on dragon side, top lane bush and the other side of wall form them, etc).

Easy:

Pick Cho'Gath, silence+nom for big burst when he's ~1/2 health. If he ults, knock up takes care of the majority of his ult and he doesn't really do much damage at all.

do people ever make a counter for tynr that doesn't work for anyone else?.
and try kiting him i've beaten tynrdameres fairly easily with katarina the trick is to rush rylias and keep dancing around him but stay out of range between shunpos so he can't chase u.

If you can get a Tyrndamere to pop his ult. Malazhar is the best choice. That CC, for 3 sec. will easily dispose of him.

The problem is getting him down to that amount of health however lol xD

rocket grab him into a turret with blitz. gg.

I think Xin is more problematic than Tryn. He can kill you quicker and he doesn't need to farm that much to get dangerous.

here is the point of this conversation, there are many ways to counter the annoying tryndamere, however, one must concentrate his/her build to stop him in which doesn't means it would help against any other people. Sure someone play tryndamere and he gets counter, but now what? all the exhaust and ignite are used and so are the stun and other CC, what is there left to use it against others that were standing right beside him. 1v1 tryndamere is easy, but in team fight, it's impossible.

Play wukong, beat him up all game. bring exhaust flash. get him low, ulti. he endless rage exhaust
win