Yeah, Tasha Yar was a butch security officer with a broken past who got killed real early on by some oil slick monster composed of purified evil (Saddam Hussein refuses to comment). Data was one of her friends it seems.
However, several seasons later, she re-appears on the Enterprise-D when an alternate universe is caused by the Enterprise-C being warped to the future because of a temporal ream. The loss of the E-C in battle causes the Klingons to hate the Federation (the C was getting its ass handed to it by the romulans defending Klingons) so the D and C get ambushed by alternate Klingons. Alternate Tasha Yar goes back in time as the captain pro tempore of the C and finishes the battle.
BUT! Later on we meet ANOTHER Yar…actually, it’s her half-romulan daughter, because it seems Yar survived the battle and was captured (which is odd for Romulans…) and this new bitch is heavily involved in the Romulan-Vulcan-Klingon love triangle. Like, heavily involved. She’s got more strings on the house of Duras than Polly-O cheese.
[without turning around] GG, if you follow through with that action, then when Ace, Yaridovich, and the other two MUCK versions of myself catch up with you, you’re going to regret having a nervous system.
Ah, don’t worry, d. I won’t kill you. Not until after I regain my normal Body, that is. As it stands, it’s more like just holding YV in my adult form under my control.
You can run, little man, but you will never be safe. I am older than dirt, and stronger than week-old coffee. Until the moment I officially give up on living- which will be in only about 60 or 70 years, if I hacve anything to say about it- will anyone be really safe.
Nyar har har harley harl harl!
Sorry, that was me.
That was inevitable. Of course, he mentioned it in his first post in this thread. Only one thing can make it worse now.
Nya?
Too late! 
deflects the shot
… See ya.