New figures released from Census 2016 have shown a near-80% increase in the number of Spanish people living in Ireland.
The 'Non-Irish Nationalities Living in Ireland' report said 10 nationalities account for 70% of non-Irish nationals.
Polish nationals (122,515 people) made up the largest group while German nationals (11,531 people) were the smallest of the 10 groups profiled.
The number of UK, Polish, Lithuanian and Latvian nationals fell between 2011 and 2016.
The largest increases were in the Spanish, Romanian and Brazilian populations.
The Spanish population increased by 78% from 6,794 to 12,112 people between 2011 and 2016.
The Central Statistics Office (CSO) said this was the biggest percentage increase of the nationalities profiled.
Romanian nationals increased by 69% from 17,304 to 29,186 during the same period and was the largest increase in population size.
The four nationalities with the highest concentration of their populations living in Dublin city and suburbs were Brazilians at 64%, Romanians and Italians each at 58% and Spanish nationals at 52%.
In city living overall, 72% of Brazilians and Italians lived in cities and suburbs - while 50% of UK nationals lived in rural Ireland.
Of the 10 nationalities in the report, the Brazilian population was the youngest with an average age of 29.9 years.
Romanian nationals were the second youngest at 30.5 years.
The two oldest populations by average age were UK nationals (46.7 years) and Germans (40.5 years).
UK nationals had the lowest labour force participation rate (59.7%), largely due to a high (19%) proportion of retired people.
Each of the other nine nationalities had a higher labour force participation rate that the State figure of 61%.
One-quarter of all metal workers and male bakers and flour confectioners in the State were Polish.
Some 18% of the Spanish population at work (1,459 persons) worked in the information and communication industry, as did 20% (1,615) of French nationals.
Renting was more common than home ownership for all but one of the nationalities profiled.
The exception was UK nationals - with 62% of households headed by a British national owning their own home.
In April 2016, there were 535,475 non-Irish nationals living here - a decrease of 1.6% on the 2011 census figure of 544,357.
Commenting on the report, senior statistician Cormac Halpin said: "One of the many benefits of census data is the information it gives us on the individual groups that make up Ireland's population.
"This report details the top 10 largest non-Irish national populations living in Ireland and looks at the characteristics of each covering topics such as where they live, age profile, education, language ability, housing, general health, work and occupations".