These commercials from Virgin Mobile actually advertises from a Yandere's point of view. She's seen sitting in a tree outside his house on a stormy night and talking about how they just had the best first date ever and she can use her phone to check on whether he's mentioned her yet and if his exes are hotter than her and that she can "check his Four Square profile for patterns." "And it's only $25 a month! That's crazy right!?" (horror lightning) Then there's a sequel to this ad featuring the same girl in another guy's closet.
What makes it worse is that if you watch Supernatural you'll realize that the actress playing her also plays Lillith, the psychotic demon who is also Yandere for Lucifer.
Hyeri from Redrum327. When Gahui became friends with Taien as a child, Hyeri rounded up the rest of the "crew" to trap Gahui in an isolated safe in a forest. She's found starved, frozen and mentally scarred six days later.
Dorothy of Oz's Abee (Codename: Scarecrow) is a sort of subverted example. Anyone who posed the SLIGHTEST threat to Mara was attempted to be pushed off a cliff, shot at, left to die in a cave, or worse. He would have continued with this, but Mara got upset at all the murder attempts. Not to mention his rivalry with Kamu who wants to protect Mara as well, and his promise to kill him if he gets out of line.
A large part of Christopher Titus' act revolves around the fact that his ex-girlfriend/ex-wife was this. As he put it at one point, when walking through the mall, he had to keep his eyes shut, or she would accuse him of eying and considering cheating with any woman he saw (including mannequins and fat men who look like they have breasts). He mentioned a situation with his new girlfriend that ended with her pulling an "inspected by #31 sticker" out of his underwear and laughing at him, whereas his previous relationship would have ended with her demanding to know who inspector #31 was.
And prior to that was an even worse woman who started fights because "I was watching the Doublemint Twins commercial too intently."
Dave from the Dating Dave web series runs into Dymphna in a bar and she seems nice and sweet...until the next day when she's apparently already got a wedding dress sorted and is planning the bridal shower. And when he says no, she leads her friends into an angry mob to chase him down the street.
Taken to extremes with SCP-1805 of the SCP Foundation, a sex doll which comes alive when a man has sex with her and which considers the man to be her "husband". On the one hand, she's so devoted to her "husband" that she'll willingly let him mutilate and dismember her. On the other hand, she's so jealous that the man spending too much time with his own children will make her go Axe Crazy. And to put a final, weird twist to it, she instantly loses all interest in her "husband" the moment he dies, since marriage is, after all, "til death do us part".
There's also SCP-1269, a mailbox which sits in front of a house in Massachusetts, USA. If a woman aged 23 or older moves into the house for SCP-1269, mysterious unaddressed letters, which are directed at the woman and highly romantic in nature, manifest inside the mailbox every four days. If you attempt to remove 1269 and replace it with a normal mailbox, both disappear, with 1269 appearing back in it's usual spot and the other mailbox appearing in a dumpster 25km away with an extremely hostile and possessive letter inside it. SCP-1269 was recently kicked up to Euclid status when a male D-Class moved into the house with the female D-Class resident only to go missing some weeks later, his battered and mutilated corpse was found in the dumpster. Examples of letters found:
1) The color of your eyes reminds me of the depth and expanse of the night sky, a vast dazzling macrocosm of soft velvet and glimmering pinpricks of light.
2) The wind was blowing and I thought it whispered your name sadly because that is what my heart is doing please write back
3) FUCK YOU YOU PILE OF PLASTIC AND WOOD SHE IS MY EVERYTHING YOU ARE NOTHING TO HER IT WAS A FLING AND I KNOW IT I'M DOING HER A FAVOR
4) YOU ARE NOTHING BUT A TOOL FOR HER USE BUT I AM MORE I AM HER EVERYTHING AS SHE IS MINE SHE USED YOU SHE USED YOU SHE USED YOU AND NOW YOU'RE WHERE YOU BELONG
5) WHAT IS A MAN BUT A PILE OF SHIT THAT GETS IN THE WAY OF MY LOVE HOW CAN SHE EVER LOVE YOU WHEN YOU'RE SO EASILY BROKEN SHE NEVER EVEN LET YOU TOUCH HER I SAW THE WAY SHE LOOKED AT YOU WITH HATRED AND NOW SHE WILL LOVE ME FOREVER
Markiplier acts like this in "Best Friends Forever" for Cinnamon Toast Ken. He tries so desperately to get in his house and makes claims about how close they are. Naturally, Ken is a little freaked out by this and does his best to keep Mark out. ...It doesn't work.
In the vein of the Yandere no Onna no Ko dramas, listed above, there are also Yandere Heaven dramas, which set the (presumably female) listener in various situations (friend, assistant in a hospital, sister, etc) with two male yanderes vying for your/her affection. An English translation is here.
An amusing case when it comes to the Vocaloid 2 engine software Prima:
Prima was given a yandere type personality by the Western fandom due to the fact that when people tried to illegally download vocaloids, such as Miku and Len/Rin Kagamine, they had to download Prima to get the program in English. However illegal downloads of Prima donít have proper confirmations codes. Causing not only Prima to stop working but other Vocaloid programs as well. Basically if the user couldnít keep her then they couldnít keep any vocaloids.
The element fluorine has been jokingly (or seriously) called the yandere element. The reason being is that unlike the other halogens (like chlorine), it has a really low bonding energy requirement. Basically, anything that fluorine can react with, and it's easier to list things that it doesn't react with, will react explosively, or at the very least much more violently than other reactions. And once it's in a compound, good luck trying to separate it. Even if you do separate it, it's very poisonous (again, due to its reactivity) and will likely kill you unless you took as many precautions as you possibly can. It's very telling just how violent fluorine is when it or certain compounds of it will either burn or melt things that protect against even the harshest of acids.