Usual suspects in indoor grows are below.
Fungus gnats - small black flies that hover around and like the top of your medium. Each female can lay 300 eggs in their lifespan. These eggs turn into larvae that like to eat roots! AZAMAX, MOSQUITO DUNKS, SPINOSAD, BT, STICKY YELLOW TRAPS are possible treatments. Predatory insects - hypoaspis miles, predatory nematodes.
Spider mites - found at the tops of plants making webs across your foliage/buds. AZAMAX, PLANT VITALITY+, MIGHTY WASH, SPINOSAD Treatments should work. Predatory insects - ladybug, spider mite predators.
Western flower thrips - small winged insects that leave silvery scratches on your leaves through feeding. SPINOSAD is the only sure method I know of eradicating these. Predatory insects - predatory nematodes, hypoaspis miles. Part of the WFT life cycle is in the medium where these predators reside.
Scale - small round balls that can go unnoticed. Sap suckers. Alcohol rub removes them.
Carpet beetles - found in most homes they look like a small brown speckled ladybug. They munch leaves. Pretty harmless in low numbers.
Springtails - detrivorous feeders, generally feeding on decaying organic matter in the medium. Small white looking crawlers that when startled jump quite a shocking distance. Pretty harmless but can freak you out. I've found using an enzyme product such as CANNAZYM along with Trichoderma fungi helps to eliminate the decaying matter starving the springtails of a food source.
That's probably the most common found in the indoor garden.
There are other not so common ones such as mealy bugs, bud worms etc.
J