In 2018, 5 is the most common age for an American (U.S.) Ian who is registered male with the Social Security Administration. It is the 307th most common male first name for living U.S. citizens.
― Anonymous User 10/16/2018
12
In my family it is quite common. My dad is Ian, I am Ian Jr and at our yearly family Coutts reunion which will be the 90th year in 2017 there have been at least 7 Ian Coutts' at the same table. Coutts being a Scottish name that we can trace back to the 1600's.
Putting down another variant of a name is utterly childish. "Iain" is the true spelling? Not if your name is Ian it isn't. This is like saying that all forms of John, including John itself, Johann, Johannes, Giovanni, Juan, Jean, Sean, Eoin -- and Iain! -- are bastardizations of the original Hebrew Yochanan -- which, historically, they are. Lighten up. There's always room for more than one version of a name.
Also Slovene: https://www.behindthename.com/name/ian/top/slovenia
Also Spanish (Modern):
https://www.behindthename.com/name/ian/top/argentina
https://www.behindthename.com/name/ian/top/chile
https://www.behindthename.com/name/ian/top/mexico
https://www.ine.es/widgets/nombApell/index.shtml?L=1
Also Portuguese (Modern):
https://pt.m.wiktionary.org/wiki/Ian
https://en.m.wiktionary.org/wiki/Ian#Portuguese
https://www.behindthename.com/name/ian/top/portugal
https://www.behindthename.com/name/ian/top/brazil