O
- Oak — Sun Java
- OberoN — Linux Smart Card Howto 1.0.4
- Obi Wan — CollegeLinux 2.5
- Oceanic — Apple Macintosh IIsi
- Odem — Intel processors
- Odin — TinySofa Enterprise Server Linux 2.0
- Odysee — Microsoft Windows 2000's cancelled successor
- Odyssey — Mandrake Linux 7.2
- Odyssey — SiS 740
- Offcampus — Sun SPARCStation SLC
- Okinawa — Turbolinux 2.0
- Omega — Apple Macintosh PowerBook 190/190c
- Oneiric Ocelot — Ubuntu 11.10
- Optimus — Apple Macintosh LC 575
- Orbit — Sun SolarNet PC-X terminal software
- Orca — Sun E4000/E5000
- Oreo — Sun Netra j 3.0
- Orion — Microsoft Windows CE 2.11 for Pocket PC version 1.1
- Orion — Yellow Dog Linux 4.0
- Orion DT — Intel 450KX
- Orion ST — Intel 450GX
- Orleans — AMD Athlon 64 90 nm processor (Socket AM2 w/ DDR2-667)
- OS04 — grml Linux 0.1
- Oslo — Sun QIC-2.5GB 1/4" Tape
- Osmium — Exchange 5.5
- Osoyoos — XMetaL Author and Developer 4.0 Trial Version
- Osprey — Sun Millennium-based workgroup server
- Othello — Sun cPCI 500 MHz USIIe CPU
- Otter — Sun Ultra 5
- Owens — Sun NetDynamics Release/Rev 5
Read more about this topic: List Of Computer Technology Code Names