The Railways Tribunal was established under the Railways Act 1924 and its powers were given to the High Court under the Transport Act 1944.
The Commissioners for Irish Lights were established in 1935. It originally derives from UK legislation from 1854.
Under the British Irish Act.1999 The Loughs Agency of the Foyle Carlingford and Irish Lights Commission. It is under the British-Irish Agreement Act 2002.
The Irish Tourist Board was formed under the Tourist Traffic Act 1939 and replaced by An Bord Fáilte in 1952.Bord Fáilte was established under the Tourist Traffic Act 1952. It was replaced by Bord Fáilte Eireann, the Irish Tourist Board in 1955.  Bord Fáilte Eireann was replaced in 2003 by Fáilte Ireland the national tourism development authority under the National Tourism Development Authority Act for 2003,
The Commission for Aviation Regulation was established under the Commission for Aviation Regulation Act 2001.
The Commission for Taxi Regulation was established under the Taxi Regulation Act 2003.
Córas Iompair Éireann was established in 1944 as a limited company under the Transport Act 1944. It became a statutory corporation in 1950 under the Transport Act 1950, formed after the dissolution of Great Southern Railways and the Dublin United Transport, Limited.  It took over the functions of the Board of Control of the Royal Canal and Grand Canal. It was reorganised in 1986 and operates through three subsidiaries.
Former subsidiaries included Aerlod Teoranta and Óstlanna Iompair Éireann Teo. The Dublin Metropolitan Street Commission was established in February 1987 and abolished in July 1987. The Dublin Transport Authority was formed in November 1986 and abolished in December 1987.
The National Sports Campus Development Authority was established in 2007 and replaced Campus and Stadium Ireland.
Horse Racing Ireland commenced in 2001 and is still active. It superseded the Irish Horse Racing Authority and its predecessor The Racing Board founded in 1945.
Tote Ireland Limited is a wholly owned subsidiary of Horse Racing Ireland with responsibility for operation of the totalisators on 24 Irish racecourses. The Irish Horse Racing Authority was active from 1 December 1994 to December 2001. It replaced the Racing Board and was replaced by Horse Racing Ireland.
The Board for the Control of Mechanical Betting in Ireland was incorporated in 1930 and replaced by the Racing Board in 1945. The Racing Board was established in 1945 and replaced in 1994 by the Irish Horse Racing Authority.
The Irish Horse Board was incorporated in 1993 and is extant. Horse Sport Ireland Limited was incorporated in 2006.
The  Irish National Stud Company was incorporated under the National Stud Act 1945 and later amended on a number of occasions.
The Railway Procurement Agency commenced under the 2001 Act. The Railway Safety Commission commenced under Railway Safety Act 2005.
The Road Safety Authority was constituted under the Road Safety Authority Act 2006.
Aer Lingus PLC resulted from the restructure of Aer Lingus and Aerlinte Eireann in 1993. Aer Lingus Group plc was privatised in [2006 ].
Aer Rianta was incorporated under the Air Navigation and Transport Act 1936, the Air Companies Act 1966. Under the State Airport Act 2004, the Dublin Airport Authority assumed responsibility for its assets.
Dublin Airport Authority commenced in 2004 and assumed responsibility for the assets and business of Aer Rianta under the State Airports Act 2004.
Cork and Shannon Airport Authority are intended to be transferred. Aer Rianta was originally the holding company for Aer Lingus and Aerlinte Eireann.
Aer Lingus was incorporated in 1936 under the Air Navigation Transport Act 1936 and was restructured into Aer Lingus Group PLC in 1993 under the Air Companies Amendment Act 1993.
Aerlinte Teoranta was incorporated in 1947 and restructured into Aer Lingus Group PLC in 1993. Aerlod Teoranta was a former subsidiary of CIÉ incorporated under the Transport Act, (Additional Powers) Order, 1964
Bus Eireann commenced under the Transport (Re-organisation of CIÉ) Act, 1986 as a subsidiary of CIÉ in 1987.
Dublin Bus commenced as a subsidiary of CIÉ under the Transport (Re-organisation of CIÉ) Act, 1986.
The Drogheda Port Company existed as the Drogheda Harbour Commissioners for over 200 years. It was incorporated under the Port Companies Act 1996/Harbours Act 1996 and commenced in 1997.
The Dublin Port Company was formed and incorporated Dublin Port and Docks Board which dated in 1867.
Under the Harbours Act 1996 Dún Laoghaire Port Company was formed under Harbours Act 1996.
Foynes Port Company merged into Shannon Foynes Port Company in 2000 under the Harbours Act 2000. It was formed under Harbours Act 1996.
Galway Harbour Company was formed under Harbours Act, 1996 in 1997.
New Ross Port Company Cork Port Company and  Waterford Port Company were incorporated under the Harbours Act 1996.
Shannon Estuary Ports was formed by the merger of Shannon and Foynes Port Company under the Harbours Act 2000. It was established from  the former Limerick Harbour Commissioners’ Foynes Port Company and which itself derive from Foynes Harbour Trustees.
Campus and Stadium Ireland Development Limited was incorporated in 1999 under the National Sports Campus Development Act and replaced by the National Sports Campus Development Authority in 2007.
Dublin United Tramways was a private company incorporated in 1896. It continued until 1941. Dublin United Transport Company Limited replaced Dublin United Tramways Company in 1941 and was ultimately assumed into CIÉ in 1945.
The Irish Sports Council was formed under the Irish Sports Council Act 1999. Cuspoir was incorporated in 1978 and replaced by the  Irish Sports Council under the Irish Sports Council Act 1999.
The Dublin Transportation Office was formed in 1995 and merged with the Transport Authority in 2009.
The  Irish Aviation Authority was established under the Aviation Authority Act 1993 in 1994.
Irish Shipping Limited was nationalised under Irish Shipping Limited Act 1947Â It subsisted from 1941 and was wound up in 1984.
The Commission for Aviation regulation was established in 2001 to provide independent regulation in certain aspects of aviation and travel in Ireland. It sets the maximum level of airport and aviation terminal service charges. It licenses travel, trade, and grants tour operators and travel agents licenses. The Commission licenses airlines and approves ground handling service provider under EU legislation. It discharges Ireland’s responsibilities for schedule, slot coordination/allocation.
The Commission for Taxi Regulation established in 2003/2012. This is responsible for the regulation and control of, operation of taxis, hackneys and limousines.
The Commissioners for Irish Lights is responsible for the delivery of reliable and efficient aids to navigation service for the benefit of all mariners. It is an all-Ireland body.  It inspects and approves aids to navigation systems and audits management provided by ports and local lighthouse authorities The body is associated with two other bodies in England, Trinity House responsible for England and Wales and the Northern Lighthouse Board responsible for Scotland and the Isle of Man. It was established under the Merchant Shipping Act.
CIE operates public transport services through its subsidiaries. It is established under Transport Act 1950 and reorganised in 1986.
The Irish Aviation Authority is responsible for the provision of air traffic management services in Irish air space. It is responsible for the safety, regulation of the Irish civil aviation industry. It is incorporated under the Irish Aviation Authority Act 1993.
The National Roads Authority is responsible for planning, supervision, construction and maintenance of national roads. Its functions include preparation and arranging road designs, maintenance programs and schemes for the provision of traffic signs on national roads, securing construction, improvement and maintenance work on national roads, allocation and payment of grants for national roads and training, research and testing activities in relation to its functions. It may direct local road authorities in connection with the construction or maintenance of a national road.
The Railway Procurement Agency has the power to procure light rail and metro infrastructure. It makes bylaws and may prosecute a range of offenses under the Transport, Railway Infrastructure Act 2001.
The Railway Safety Commission (Railway Safety) Act 2005 regulates railway safety. It is responsible for matters of railway and cableway safety on passenger-carrying systems and freight carrying systems where they interface with public roads.
The Road Safety Authority (Road Safety Authority Act 2006) is responsible for the promotion of road safety, road safety research, driver testing, licensing, vehicle standards, road haulage, enforcement functions, registration of driving instructors, driver vocational training and compulsory basic training for the motorcyclists.
The National Transport Authority is involved in the supply of various public transport and related services in Ireland, ether as contractors public service obligation contracts as with Dublin Bus, Bus Éireann and Iarnrod Éireann,  through subcontracting as with Luas system contracted on behalf of the Railway Procurement Agency or as licensing authority in relation to commercial bus and small public service vehicles, i.e. taxis, hackneys and limousines.
The National Transport Authority seeks to develop the transport for Ireland service as a one-stop-shop. Alongside real-time passenger information, it has developed a national journey planner and delivered an integrated ticketing project.It is charged with devising projects to enhance people’s use of public transport and sustainable transport choices in line with government policy. It has responsibility for capital investment in the Greater Dublin area (2008 Act) and for projects for promoting sustainable transport nationwide. The Authority has a range of functions in relation to transport, planning and policy. It publishes a strategic transport strategy, an integrated implementation plan and a strategic traffic plan.