Sir Robert John Thomas, 1st Baronet (23 April 1873 – 27 September 1951) was a Welsh businessman and Liberal Party politician, who was twice elected to Parliament.
Thomas was a ship and insurance broker. In 1918 he was created a Baronet, of Garreglwyd in the County of Anglesey.
He was elected at the 1918 general election as the Member of Parliament (MP) for the new constituency of Wrexham. Standing as a Liberal, with the official backing of the David Lloyd George led Coalition Government, he faced only a Labour Party opponent and won 76% of the votes.
At the 1922 general election he stood as a National Liberal Party candidate for Anglesey, losing by a margin of 9% to the sitting Labour MP Sir Owen Thomas.
However, Owen Thomas died in January 1923, and at the resulting by-election in April Robert Thomas won a 3-way contest with 53% of the votes, and a 23% majority over the second-placed Labour candidate.
He was returned unopposed at the general election in December 1923. He was returned by a majority of 28% over his Labour opponent at the election in 1924.
He stood down from Parliament at the 1929 general election.