For the fishes called midshipman, see Midshipman fish

In the navies of English-speaking countries, a midshipman is a low-ranking commissioned officer, usually the lowest rank.

In the Royal Navy, the rank of midshipman is one of the oldest ranks. It is the lowest rank of officer (apart from officer cadet), but is technically a rate in that it is not conferred by commission or warrant but by entry in a ship's books, and can be removed summarily. In previous times midshipmen were considered to be of warrant rank.

A Royal Navy midshipman ranks immediately below a Second Lieutenant in the Army or Pilot Officer RAF. His rank insignia is a white patch with a buttonhole and gold button on each lapel

In the United States Navy a Midshipman is for all intents and purposes an officer cadet although the rank is still an appointed officer rank in the Navy. The term "cadet" is incorrect and inappropriate as in the Navy and Marine Corps, a "cadet" refers to a high school student in NJROTC. The collar and sleeve insignia varies by school year, but officers' uniforms are worn. A Freshman wears no collar insignia, a Sophomore wears a single fouled anchor on the left collar, a Junior two fouled anchors, and a Senior wears eagles perched on fouled anchors, or an officer rank. Shoulder boards and the lapels of the service dress blue uniforms have a gold anchor, except for Midshipman officers, whose shoulder boards have a small gold star and horizontal stripes indicating their rank. Midshipmen officer ranks are those of the U.S. Navy, but the collar insignia are gold bars, for the ranks of Midshipman Ensign (one bar or stripe) to Midshipman Captain (six bars or stripes), in the Brigade of Midshipmen at the U.S. Naval Academy, with the highest Midshipman grade being Midshipman Commander for Navy ROTC and the U.S. Merchant Marine Academy. A Naval Academy Midshipman receives about $750 a month for expenses, but it is usually greatly reduced by books, barber, and uniform bills. NROTC Midshipmen receive a $250 to $400 monthly stipend if they are on scholarship. All NROTC Midshipmen receive uniforms, typically service dress blues, summer khakis, summer whites and dress whites. Some units may issue camouflauge utility uniforms to the majority of students, but all Marine Option students receive them.

The Midshipmen is also the name for sports teams fielded by the U.S. Naval Academy.

The word midshipman derives from the part of ship between the bow (front) and stern (back), "amidships," which was their station.

U.S. Navy Midshipman Insignia

Note: NROTC refers to Naval Reserve Officer Training Corps

See Comparative military ranks