Merwin, Hulbert, and Co. or Merwin Hulbert was an American firearms designer and marketer based in New York City which produced revolvers and rifles from 1874 to 1896. The firearms were manufactured by a subsidiary company, Hopkins & Allen of Norwich, Connecticut. Merwin Hulbert's designs had influenced other gunmakers of the time, such as Meriden Firearms Co., Harrington & Richardson, Forehand & Wadsworth, and Iver Johnson.

During the late 19th century, Merwin Hulbert revolvers were used by police departments of many cities in the eastern United States.

Joseph Merwin was involved with marketing and manufacturing revolvers as early as 1856 when he formed an arms company known as Merwin & Bray. This company folded after the end of the Civil War. In 1868 Merwin formed a partnership with William and Milan Hulbert, who owned 50% interest in Hopkins & Allen. Merwin and Hulbert not only designed firearms, but imported firearms and retailed firearms and other goods in a large sporting goods endeavor. Merwin and Hulbert additionally purchased several firearms manufacturers. Author Art Phelps opined that if Merwin and Hulbert had not marked the revolvers with the manufacturers name 'Hopkins and Allen' (known for inexpensive and poor quality weapons), the Merwin Hulbert would be as well known as Colt, Smith & Wesson, and Remington.

The company made numerous innovative designs such as folding hammers on their revolvers for pocket carry and a unique takedown system but was plagued by financial missteps. Payment for three sizable shipments to Russia were never realized. The bankruptcy of subsidiary Evans Rifle Company cost Merwin and Hulbert $100,000. A company associate stole the firm's operating capital and disappeared. During 1880–1881, Merwin and Hulbert was in receivership, but it was able to recover.

After Merwin's death in 1888, the company became known as "Hulbert Brothers & Company". Hulbert Brothers declared bankruptcy in 1894 and in 1896 it was liquidated. Hopkins & Allen continued to manufacture Merwin Hulbert style rifles, primarily .22 and .32 caliber single shots, until 1916 when it went bankrupt and was bought the following year by Marlin Firearms.

The company developed a nickel plating process superior to their competitors, which was even less expensive than providing bluing. The nickel acted to protect the metal surfaces from corrosion. Because nickel-plated Merwin and Hulbert pistols had the same cost as those without, it is rare to find Merwin and Hulbert revolvers with a blued finish.

A key innovation was a rotating barrel design which allowed the user to rotate the barrel 90 degrees in order to pull the barrel and cylinder forward to remove the fired cartridge cases. During the twisting motion, the empty case could be extracted. Any intact cartridge would remain in the chamber due to the additional length of the bullet. The tight machining tolerances would create a vacuum when the barrel and cylinder were pulled forward, literally causing the assembly to 'snap back' closed when released. In addition to this unique case extraction system, pressing an additional lever control when the frame was 'open' for extraction allowed the owner to completely remove the barrel. Note: early models also required pushing out a barrel wedge similar in function to Colt percussion revolvers. This not only facilitated cleaning, but allowed the owner to swap barrels, allowing for a shorter 'concealed carry' and longer 'field' weapon in one. The combination of extraction and barrel removal required very precise manufacturing tolerances—incredible considering the tools of the day.

According to Arthur Corbin Gould, Merwin Hulbert revolvers were considered to be the strongest revolvers made during the late 19th century.