Matheson Lang (1879–1948) was a British actor, actor-manager and playwright, and a pupil of F. M. Alexander.
Matheson Lang began his career in 1897, and first played in London in 1900. He became well-known for his Shakespearen roles, playing Othello, Hamlet and Romeo, among others. He worked with Sir Frank Benson, Lillie Langtry, Ellen Terry, Oscar Asche (also a pupil of Alexander) and Nora Kerin (also a pupil of Alexander). He performed as Romeo with Nora Kerin as Juliet in 1908.
Between 1910 and 1913 Lang and his wife (the actress Nelly Hutin Britton) formed their own company, which toured India, South Africa, and Australia performing Shakespeare.
In 1916 Lang starred as Shylock in a film version of The Merchant of Venice, with his wife as Portia. He went on to appear in over 30 films and was one of Britain’s leading movie stars of the 1920s. He was famous for playing Matthias in The Wandering Jew, which had a very long run in several theatres and on tours, and later made into a film (1923). He was also so successful for playing the title role in Mr Wu (1919), that he titled his memoirs Mr. Wu Looks Back.  
Connection with Alexander
In an advertisement flyer F. M. Alexander quotes a letter received from Matheson Lang:
26th November 1909
Before leaving for America I want to thank you for all that your work has done for me, and for all the trouble you have taken on my behalf – and also to express my admiration for the work you are doing, which has such wonderful results.
I have derived great benefit from it in every way, and in my recent severe attack of influenza during the run of Hamlet I should never have been able to keep on playing so exacting a part had it not been for you.
I can never thank you enough for that – for it naturally meant a great deal to me in that particular part.
With best wishes and kind regards,
Your sincere friend,
Matheson Lang also relates the help he derived from Alexander in his 1940s memoirs:
It was during the run of Hamlet that I first met that very remarkable man, F. Matthias Alexander. I went to him for help with my voice, which, after the strain of Pete [in 1908] was giving me trouble. He was then working on voice production and had given invaluable help to a number of leading actors and actresses in London. Even then at that early stage his work went far beyond mere production, and since has grown into the remarkable thing that has for its cope the whole co-ordination and use, according to his methods, of the human body. In those early days of Hamlet he helped me enormously, coming night after night to the theatre to see me safely through the performance, which in that enormous building was a tremendous nervous and physical as well as vocal strain, and from that help has grown a friendship which has lasted ever since.
Lang was a friend of Sir William Arbuthnot Lane, who was also a pupil of F. M. Alexander.
Walter Carrington on Matheson Lang
Walter Carrington relates a story which he had been told by Mrs Lang. The story relates how F. M. Alexander lost patience with Matheson Lang in early lessons because Lang was not paying attention, and after a final warning Alexander threw Lang out. However, Lang returned later and resumed lessons. Carrington also relates the story of Alexander threatening to throw a book at Lang if he pulled his head back.
Matheson Alexander Lang *15 May 1879 – †11 April 1948.
Reference in the Alexander Technique literature
The Alexander Album by Francesca Greenoak contains a short bio of Matheson Lang.