There are at least two artists with this name:
1) Ian Thomas (Canadian, active 1970's-Present)
2) Ian Thomas (American, active 2000's-Present)
3) Ian Thomas (Belgian, active 2011's-Present)

1) Canadian Ian Thomas:

Ian Thomas (born 23 July 1950, Hamilton, Ontario, Canada) is a Canadian singer, songwriter, actor and author. He is younger brother to famed Canadian comedian and actor Dave Thomas.

Thomas was a successful rock and roll musician in Canada during the 1970s, with his most memorable hit being 1973's "Painted Ladies". Success in the American market, however, has proven to be elusive with the possible exception of "Painted Ladies," which remains his only U.S. Top 40 hit. He has also done musical composition for about a dozen films and television shows. Before breaking through with "Painted Ladies", he was a producer at the CBC. Before that, he was part of the folk music group Tranquillity Base.

Many of his songs have been covered by popular artists, including "Hold On" (Santana), "The Runner" (Manfred Mann's Earth Band), "Right Before Your Eyes" (America), and "Chains" (Chicago). In 1988, Daryl Braithwaite had hits in Australia with two Thomas compositions: "As The Days Go By" (which peaked at #10), and "All I Do" (a #12 chart hit).

From 1991 through 2002, Thomas released four albums with The Boomers.

Currently, he performs with Murray McLauchlan, Cindy Church and Marc Jordan in the group, Lunch At Allen's.

2) American Ian Thomas:

After traveling for years as a street performer, Ian Thomas began playing clubs in New York City, where he recorded his debut album "A Young Man's Blues" and his follow-up "Live at Rockwood Music Hall". Performing both solo and with a band, Thomas draws on a variety of American roots influences, delivering his original compositions on guitar, harmonica and kazoo. His latest release is the EP "Live at the Grey Eagle" recorded in Asheville, NC. He is now based in Knoxville, TN.

3) Belgian Ian Thomas:

Ian Thomas Hoelen (born April 30, 1997 in Antwerp) is a Belgian singer-songwriter, musician, actor and model currently based in Calabasas, California. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.