A spider, Missulena occatoria (Australia).
Myth: "Arachnid" is just a fancy name for spider.
Fact: There are eleven orders of arachnids. These include the scorpions; mites and ticks; harvestmen; pseudoscorpions; whipscorpions; solpugids; and spiders. It's like the relation of beetles with insects: beetles constitute one order of insects, the Coleoptera, but not all insects are beetles. Similarly, not all arachnids are spiders.
Examples of 6 of the 11 orders of arachnids. Only one is a spider.
A whipscorpion, Abaliella dicranotarsalis.
A scorpion, Charmus indicus (India).
A pseudoscorpion, Chelifer tuberculatus (Algeria).
A harvestman, Phalangium opilio (worldwide).
A solpugid, Ammotrechella cubae (Cuba).