For other meanings, see Regent.

Regent is a trademark for a broad spectrum systemic insecticide containing the active ingredient fipronil. Fipronil is an insecticide discovered and developed by Rhône-Poulenc between 1985-87. It was placed on the market in 1993. Regent's rights have been purchased by BASF. It acts by contact and stomach action on the insect. Fipronil is marketed in many developed and developing countries.

Regent has contact activity on both chewing and sucking insects and controls Coleoptera, Lepidoptera, Diptera, Homoptera, Isoptera, and Thysanoptera. It is registered on rice (seed treatment), and corn (soil treatment), with potential uses on cotton, sweet potato, bulb onion and potato. It is being studied for use against lygus bug on cotton and thrips in vegetables.

Regent is effective against a variety of pests, but there are increasing concerns about its environmental and human health effects. Its use has become problematic in France, where it has been considered responsible for the drop in bee population, after bees became disoriented and unable to return to their hives.

Maurice Mary, vice-president of the National Union of French Beekeepers (UNAF) was quoted as saying, "It's enough for the insect to alight on the plant to receive a dose of neurotoxicity. All the auxiliary fauna is decimated."

Fipronil is/was also employed under tradenames, for other purposes, for example, cockroach and ant control under the trade names Goliath and Nexa, Chipco Choice for golf courses and commercial turf, and Termidor for termite pests. It is also a component of the trademark insecticide Frontline or Top Spot, which is used for flea, tick, and mite control.