Is the surname "Beltran" a corruption of Bertrand? There was a saint for which Wikipedia gives the following names;
Saint Louis Bertrand, O.P. (Spanish: Luis Beltrán, Luis Bertrán) (1 January 1526 – 9 October 1581) was a Spanish Dominican who preached in South America during the 16th century, and is venerated as a saint by the Catholic Church.
(I was searching for famous people with the surname Beltran, if you know the etymology of Beltran, it would be cool)