Australia and New Zealand
In Australia and New Zealand a Station Officer is a career / permanent Officer who is either the single Officer on a Watch / Platoon / Shift system in a single or dual-fire apparatus/appliance station, with three to five firefighters reporting to them, or one of several Officers under a Senior Station Officer at a station with multiple appliances.
In New Zealand the rank badge is a single impeller; in Australia, the rank badge is two impellers. Station officers in New Zealand wear red helmets with one blue stripe (prior to November 2013, they were yellow with one blue stripe).
In Queensland Fire & Emergency Service (QFES) (Fire & Rescue division) there are three Station Officer (SO's) ranks Station Officer 1 (SO 1), Station Officer 2(SO 2) and Station Officer 3(SO 3) and these ranks reflect the older Station Officer ranks of Sub-Station Officer, Station Officer and Senior Station Officer. Each of these ranks has various pay points within them. QFES SO's wear a yellow helmet with a single red stripe for SO 1 and a double red stripe for SO 2's and 3's.
In the Country Fire Authority (CFA) and Metropolitan Fire and Emergency Services Brigade (MFB) Melbourne, Australia, a Station Officer has one impeller, and a Senior Station Officer has two impellers.
Although variations still occur at the Station Officer level within the different State Fire & Rescue services due to competency, experience and qualification requirements, the Australasian Fire and Emergency Services Authorities Council (AFAC) has ensured that at the Senior Station Officer level the requirements across Australasia are generally consistent throughout all jurisdictions.
Generally, (Australasian) Station Officers are made competent to perform the job requirements of the next higher rank within the respective State systems e.g; Leading Firefighters (L/Ffs) can perform the role of a SO 1 and SO 1's can perform the role of an SO 2 and SO 3's can perform the role of Inspector, if required.
In some States systems, Senior Station Officers can also in rural and semi-rural environments play a mentoring role across and for a diverse range of career/permanent, auxiliary/retained and volunteer firefighting personnel.
In the United Kingdom, a station officer used to command a station or be responsible for several watches commanded by sub-officers (although they may have commanded a watch on a very large station). The rank badge was two impellers; they also had a white helmet with a half-inch black band around it.
More recently (2006/2007), the UK FRS has changed from a rank-based system to a role-based system. This change has meant the traditional ranks have gone and been replaced by a role-based name for the duty performed. The two impeller marking now represents a watch manager. A watch commander (also referred to as a watch manager) is an officer who leads groups of firefighters and sometime in charge of a station. A station commander or station manager is an officer in charge of one or more fire stations. 
Republic of Ireland
The Fire Services in the Republic of Ireland also use the rank of station officer. In the full-time brigades of the five cities, they fulfil the role of watch manager, whereas in the retained county brigades, they fulfil the role of station commander. Rank markings are two impellers, and on the fireground a white helmet with black comb and one black stripe.
In the United States, "station officer" is often a general term and has several meanings. It usually refers to the senior officer at the station, often a captain or a lieutenant. A station commander is an officer in charge of one or more fire stations, often referred to as a district chief in North America. If a battalion or district chief works out of a station, a captain or lieutenant is still usually the officer in charge of the day-to-day operations of the station. In some cases the term "station officer" is used to differentiate between an officer who works in the field and a staff officer.
In many areas there is a captain on every shift (watch) at a station. This means that each shift has its own station officer. In some departments there is a designated officer who is in overall charge of the station.