I have assembled the following information from my collection of audio, video and print interviews to the best of my knowledge. Being only a fan, though, I cannot guarantee accuracy and correctness. For questions, additions, or corrections, go here.
Mark was born September 25, 1951 in Oakland, California, as the middle child of seven - he grew up with two brothers and four sisters. His father was in the United States Navy and the family had to move frequently, so Mark spent his childhood in many different places, from Virginia to New York to Yokosuka, Japan, where he graduated from High School.
He was member of the theater groups at many of the schools he attended, and when he moved back to Los Angeles, he majored in Theater Arts at Los Angeles City College. He began to go to auditions, landing one of his first acting jobs on The Bill Cosby Show. This was followed by several months as a recurring character on the soap opera General Hospital.
He quickly collected credits in a wide range of series, from The Streets of San Francisco to Petrocelli, and played in several direct-to-TV movies such as Circumstantial Evidence or The City.
His first role in a major feature film on the silver screen was Luke Skywalker, the aspiring young Jedi Knight of the three classic STAR WARS movies (1977, 1980 and 1983). Although this role brought him international super-stardom, it is only a small part of his resume.
He starred in movies such as The Big Red One and Corvette Summer. In December 1978, Mark married Marilou York. They have three children: Nathan (33), Griffin (30), and Chelsea (24). In the 1980s, Mark set his sights on the theater stage, where he spent nearly seven years. His credits include Amadeus, The Nerd, The Elephant Man, Room Service, and Harrigan n' Hart. The latter earned him a Drama Desk Nomination as Outstanding Actor in a Musical.
Upon his return to Hollywood, he focused back on movies and TV, adding to his resume among many others Village of the Damned or Commander Hamilton. He also guest-starred in hit sitcoms like 3rd Rock from the Sun and sci-fi series such as SeaQuest DSV and The Outer Limits. Broaching new terrain, he portrayed the lead hero Christopher Blair in the successful Wing Commander series of video games and began voiceacting.
He had already done voices in the 70s, for Hannah Barbera's Jeannie and Ralph Bakshi's Wizards, but had then concentrated on movies and television. In the early 90s, he was cast as Ferris Boyle on an episode of Batman: The Animated Series. He was then invited to audition for Batman's arch-nemesis, The Joker, and got the role. His brilliant job on the character made him a sought-after voiceactor and today he is one of the top voiceover artists in Hollywood for cartoons, animated movies and video games.
He worked as voice-director on movies such as Aero-Troopers and produced a stop-motion animated satire called The Wrong Coast. He's been voicing steadily ever since, for example for such hit cartoons as Super Robot Monkey Team, Avatar: The Last Airbender, Codename: Kids Next Door, and Metalocalypse, to name just a few.
In 1997, he also published his five-issue comic book series The Black Pearl, which was received very well. He has occasionally worked on other comics, too, such as one of Bongo Comics' Treehouse of Horror Simpsons Halloween specials.
In 2003, he returned to theater as Michael Minetti in the Richard Alfieri play Six Dance Lessons in Six Weeks. The play had a very successful run in Miami and went to Broadway the same year.
In 2004, Mark released his directorial debut Comic Book: The Movie. He did not only direct, he also wrote the script and starred as the lead character, Donald Swan. In February 2005, Mark was nominated for Best Actor and Best Director for his work at the DVD Exclusive Awards. Comic Book: The Movie eventually won the award for Best Live-Action DVD Premiere Movie.
He acted in independent movies like Reeseville or Thank You, Good Night, and did the promotion racket for The Big Red One: The Reconstruction, the restored version of the 1980 theatrical release in which he starred as Private Griff.
All throughout Summer 2007, Mark was host to his own radio show, Better Things. He was celebrity guest at the STAR WARS Celebration events in London (2007), Tokyo (2008), and Orlando (2010).
Alongside his various other projects, Mark has continued voiceacting. He has, for example, reprised his iconic Joker to raving critics for Batman: Arkham Asylum and its sequel game, Arkham City. For Asylum, he won the Interactive Achievement Award 2010 for Outstanding Achievement in Character Performance and was also nominated as Best Voice in the Spike Video Game Awards 2009.
Aside from working on bringing his Black Pearl to the cinema, Mark has been back to the small and big screen in the last three years. In 2011, he was on Season 5 of Chuck. In 2012, he shot both Airborne and Sushi Girl, both now available for purchase on Blu-ray/DVD. In March 2013, he cameoed on The Neighbors. In May 2013 he starred in the two-hour season's finale of Criminal Minds.
Considering his breathtaking pace, I'm excited to see what he's up to next. You probably all know the rumours about his potential return as Luke Skywalker, so at some point in the next few months there should be denial or final confirmation on that. But of course there's always so much more on his plate, so make sure to check back here regularly for the latest news.