If we are talking about an animal, then we can select any organism from Kingdom Animalia, their size can be vary from little sponge to large whale.
Here, For our this particular question, we can take any insect like cockroach as an example. It is considered under phylum "Arthropods" & they are most abundant species on the planet. We know, there are about 1.8 million known organisms & this is very weird fact that Arthropods make 70% of them, so they are very away from extinct categories & hence can't be extinct in future as compared to other species
Hope this helps!