Earlier, I observed a cricket jumping in the water by itself and then all these horsehair worms emerging from it.
https://www.inaturalist.org/observations/391125477
For some reason, I didn’t feel like swimming there anymore 
I think I’ve gotten all the possible animal-plant-fungi combos at this point:
Fungus parasitizing animal:
https://www.inaturalist.org/observations/365243270
Fungus parasitizing plant:
https://www.inaturalist.org/observations/351229225
Fungus parasitizing fungus:
https://www.inaturalist.org/observations/406226588
Animal parasitizing animal:
https://www.inaturalist.org/observations/308081411
Animal parasitizing plant:
https://www.inaturalist.org/observations/405377467
Animal parasitizing fungus:
https://www.inaturalist.org/observations/298781473
Plant parasitizing plant:
https://www.inaturalist.org/observations/391171962
Plant parasitizing fungus:
https://www.inaturalist.org/observations/300449570
No true plants parasitize animals, so here’s a bonus Ciliate parasitizing Ciliate:
Dragonfly mites (3+ on ventral thorax behind legs) on a young male Familiar Bluet.
Looks like a whole spectrum, but now you need plant parastizing animal (but does that even happen???)
Unless you count algae (like Prototheca), then no.
I currently have no parasite observations (I’m new), but here are some I’ve seen:
Horse leech (it was 7 inches long! 
)
Ticks( several species)
Fungi growing on ladybugs
I’ll definitely add things like these if I ever see them again.
Speaking of parasites, what is it that makes flies’ abdomens swell up and turn white? I often find dead flies in this condition.
that can be an “entomopathogenic” fungus (=insects disease causing as per the name) and this is a well known thing, just looking the right place. They erupt between the abdominal tergites
Only fungal parasites for me. I’ve got one parasite orchid I can’t geotag so not in iNat
I got bonnet pin mold https://www.inaturalist.org/observations/401475597
Would parasitic ants count? Lasius fuliginosus is a temporary social hyper-parasite—its queens infiltrate and take over colonies of Lasius umbratus, which in itself is a parasite of Lasius niger.
I observed these ants on Guernsey, which was actually a rediscovery, as they had only been noted in much older Guernsey literature. I think the reason they have been so overlooked is because the colony is on private property (I had to knock on a door to get permission to take photos), combined with the low surface area of the island limiting the availability of host L. umbratus colonies.
I had actually spotted them years ago at a family garden party just as I was getting into ant keeping, but I didn’t think much of it at the time. This summer, I was corresponding with Andy, who mentioned he hadn’t managed to find them on the island yet. That prompted me to track down the original property, ask the owners, and successfully log the colony. Funny note that colony was huge! Spanning 3+ trees and the entire backyard.
You can see thousands of observations of parasitism by searching for the observation fields Being parasitized by and Interaction->Parasitised by. Enter you taxon of interest to search for parasites of that particular taxon. I encourage you to use these observation fields in your observations of parasitism so that interested people can find them more easily.
I have observed five species that are parasites of lichens. One example is Clypeococcum hypocenomycis which is a parasite of Common Clam Lichen.
Another way of getting a list of most of the parasites you have observed is by two projects: plant-diseases-umbrella-complete and substrate-habitat-or-niche-specific-fungi-umbrella. These projects do cover more than parasites, but that depends on how you view what parasites are. I tend to view things like leaf miners as parasites because they do do damage to their hosts without killing them. If you see words like fungicolous or lichenicolous you are definitely dealing with parasites though.
A plant can be a predator of animals. Specifically carnivorous plants such as pitcher plants or sundews that prey on insects.
I have a couple!
Kangaroo Tick on the face of an Eastern Wallaroo
https://inaturalist.ala.org.au/observations/171748582
Marine leeches attached to the head and gills of fish
https://inaturalist.ala.org.au/observations/335698499
https://inaturalist.ala.org.au/observations/335699378\
Mansonia uniformis mosquito feeding from my thumb
Those are some really pretty polistes morphs! Do you know what species?
https://www.inaturalist.org/observations/171987591
Aphid infested by a wasp from the Braconidae family.
@antsbyleo, thanks… those are both Northern Paper Wasps (Polistes fuscatus). The second one has its own observation here: https://www.inaturalist.org/observations/320403899.
here is a particularly interesting parasite i think, i saw this tree in the philippines covered in little mushroom looking growths on many of the leaves
i’ve never seen anything like it and unfortunately it hasn’t gotten a lot of attention from identifiers
i also saw an incredibly cool salticid corpse with genus gibellula fungus growing out of it
