Beta helix
J1, J01, J.I, J-I or J-1 may refer to:
- J-I rocket, a Japanese solid rocket expendable launch vehicle
- J1 type submarine, a WWII Imperial Japanese Navy cruiser submarines class
- HMS J1, a WWI British submarine
- J-1 visa, a type of U.S. visa for exchange visitors (e.g. students coming to the USA for an internship)
- J-1 World Heavyweight Championship, a wrestling competition
- AEG J.I, a World War I German ground attack aircraft
- Albatros J.I, a 1917 German ground-attack single-engine biplane aircraft
- ATC code J01 Antibacterials for systemic use, a subgroup of the Anatomical Therapeutic Chemical Classification System
- DSER Class J1, a Dublin and South Eastern Railway Irish steam locomotive
- Haplogroup J1 (Y-DNA), a Y-DNA haplogroup
- Janko group J1 in mathematics
- Junkers J 1, a 1916 German aircraft
- Junkers J.I, a 1917 German aircraft
- Lawrance J-1, an early 1920s engine used in American aircraft
- LB&SCR J1 class, a British LB&SCR locomotive
- PRR J1, an American PRR steam locomotive
- S/2003 J 1, a former name for Eukelade, a retrograde irregular satellite of Jupiter
- J1 Live Concert DVD, a DVD release by Chinese singer Jolin Tsai
- J1 denotes the Personnel, or Human Resources function of a U.S. Joint Command (for example: the J-1 Directorate in Special Operations Command Europe refers to the Human Resources Directorate)
- First-order Bessel function of the first kind,
- a shorthand for J. League Division 1 in Japanese Football
- J01 : acute sinusitis ICD-10 code
- J1 (glider) refers to a Yugoslavian glider