I've never personally owned a pet and really, every pet you get should be memorable, but my attachment to pets generally varies since I'm never the sole owner. My family has owned some pets I will never forget.
-G Hawk (dog)-he lived to a ripe old age and when he became senile our cat would lead him back home. We had him for an insanely long time. I regret any and all the mean things I said about him when he pooped on the carpet.
-Chester (cockatiel)-he's not actually mine (belongs to my sister, in fact) but I'll still never forget him. He's such a silly bird (tho sometimes too loud). He talks, meows, and sometimes behaves like a bat. Also kind of affectionate.
-Emmitt (cat)-he's really sweet but scared of strangers. He's very affectionate too. He's not as playful as other cats but he has shown a hatred for socks and milk rings.
I had a cat named Jetta not long ago, but... She died recently, I think to feline leukemia, and it hurt. We got another kitten after her death for my family and our other cat, and sometimes it feels like Jetta is alive through that kitten honestly.
I'll never forget her, she was absolutely beautiful. Her coat looked like autumn leaves. I can't remember her breed though...
I had a dog named Lupi. He was a black cocker spaniel who was really attached to us. One day, however, we accidentaly left the doors opened and he ended up running away from home. We tried to spread the "Missing" posters, we announced it to the local radio, and we had some people calling us saying that they may have saw him here and there, but we had no luck.
Nowadays I am close to my cats and my other two dogs, but Lupi will always remains on our memory~
It wasn't too long ago, my sister wanted so much to have a little puppy, and we ended up getting one. At first I didn't like the thought of having a dog (I had some sort of phobia), but then I started to get along with her and I got used to her in a nice way... At least for the weeks it lasted. My mom said it was too much effort to take care of a dog, so we sold it. Even if it wasn't for a long time, that puppy will always be in my memories. I don't know why, but having her at home felt so much comfortable, it felt so nice to have a little friend here, with us.
The worst of all is that the new owners of the dog apparently gave her some bad food, and they had to take her to the pet hospital. I haven't heard of her since then. I just hope they didn't manage to kill her. >:V
I had a cat five years ago, I guess, named Pucca. We stayed with her for two years. She always got out, but not everyday. One day we let the front door open for her to get out, but some days later she never came back again. I waited for some days to see if she'd ever come back, but she didn't. I always wondered what would happen to her to this day. She will always be in my memories...
I also had a dog which was playful, but some months later she was sold. I miss her as well.
When I was 8 I (i.e. my dad) bought some fish in a bag at a fair. I was really excited to finally have pets. I named them after my cousins. The next day when I came home from school, my parents claimed they had died while they were on their way to get a fishbowl. I always thought that was a lie and that they gave them to someone else or flushed them because they didn't want me (i.e. them) to take care of pets.
My family picked up some Ghost Crabs in the beaches of North Carolina about a year ago at a bluegrass festival. We had stuck them in a very heavy box filled with sand and driven it home, where my dad and I got to carry them in. Our aunt had an old fishtank that she wasn't using, so we ended up taking that and sticking it in the room I share with my brother.
Now, we didn't actually have any free space in there, and the only possible place was a long dresser that held our underwear, socks, pajamas, and undershirts. On top was an old TV I use for my Gamecube and a box filled with my games. The game box was put on the floor and my TV was pushed to the very far end of the dresser, where now I can't see it without sitting on the far edge of my brother's bed, due to the various posts and stuff holding my bed up (it's a bunk bed). Mario Kart: Double Dash and Super Mario Sunshine are probably somewhere under the dresser, sadly (unless we sold MK, in which case ;_;). All the ghost crabs died a couple months ago, and that stupid tank is still on my dresser.