Patrick Stewart, of Star Trek, X-Men, and countless stage Royal Shakespeare Company productions, posted a picture of himself expressing support for retired-Shrewsbury lecturer Noel Conway's legal challenge.
Mr Stewart was pictured holding a sign bearing the hashtag "#ImwithNoel".
The sign included the message: "We all deserve the right, with appropriate conditions, to go when and how we choose. Support Noel."
Mr Stewart also tweeted a message of support and his own thanks for Mr Conway's efforts.
Mr Conway, 67, was diagnosed with amyotrophic lateral sclerosis (ALS), a form of motor neurone disease, in November 2014. His condition is incurable.
He wants the law changed to allow him to choose to end his own life. He has been granted a judicial review with a hearing taking place at the Royal Courts of Justice this week and a ruling expected later this year following the conclusion of this week's hearing.
Mr Conway is unable to attend in person due to his worsening health.
Today, he was watching part of the hearing via video link from Telford County Court.
Mr Conway has previously spoken of how the law is taking away his human rights.
He said: "I have lived my whole life on my own terms, in control of the choices and decisions I make. Why then, when I am facing my final months, should these rights be stripped away from me, leaving me at the mercy of a cruel illness?
"I know I am going to die anyway, but how and when should be up to me. To have the option of an assisted death available in this country would provide me and countless others with great reassurance and comfort. It would allow me to decide when I am ready to go, rather than be forced into a premature death by travelling to Dignitas at great emotional and financial cost, or to suffer a traumatic, drawn out death at home."