Trivia

His name is pronounced "Yo-wahn Griffith".

Was already an accomplished singer and oboist by the age of 13.

Lived in London for sometime with good friends and fellow Welsh actors Matthew Rhys and Michael Sheen.

First language is Welsh.

Met his first wife, actress Alice Evans, on the set of 102 dálmatas (2000), although at the time she was romantically involved with Pablo Picasso's grandson, Olivier Widmaier Picasso.

Has two children, both daughters, Ella Betsi Janet, who was born on 6 September 2009 and Elsie Marigold, who was born on 13 September 2013.

His parents Peter and Gillian were teachers and his grandparents ran a local amateur drama society in Cardiff, Wales.

Graduated from the Royal Academy of Dramatic Art in London, England in 1995.

Was invited to and accepted into Gorsedd y Beirdd Ynys Prydain (the Welsh Bardic Order of Great Britain) at the highest rank in the National Eisteddfod at Meifod in 2003, with the bardic name Ioan.

Learned Yiddish for his role in the film Solomon and Gaenor (1999).

Very good friends with fellow actors Jamie Bamber and Matthew Rhys.

An Associate Member of Royal Academy of Dramatic Art (RADA).

Resides in Los Angeles, California.

Had the honor of lighting the National Millennium Beacon for Wales in Cardiff City Centre for the New Year's Eve 2000 celebration.

Has dual British and American citizenship.

In addition to playing Mr. Fantastic/Reed Richards in Los 4 Fantásticos (2005), he provided the voice of Mr. Miracle/Scott Free for the animated Liga de la justicia (2001) series. Ironic, given that Mr. Miracle is owned by DC Comics, rival of Marvel Comics, which owns the Fantastic Four, and both characters were created by the late Jack Kirby.

Is one of three children. He has a younger brother, Alun and a younger sister, Siwan.

Won the BBC Radio Cymru Showbusnesan Award for Best Actor (March 28, 2001).

He played the oboe in the South Glamorgan Youth Orchestra for several years.

Appeared in British pop group Westlife's music video for their 2001 hit song, "Uptown Girl" alongside fellow actors, Robert Bathurst, Crispin Bonham-Carter, Tim McInnerny and James Wilby.

Has portrayed a medical examiner in two different television shows, Forever (2014) and Harrow (2018).

Has been in a long-term relationship with actress Bianca Wallace since 2021.