Of course, most people would see acting as a young person's profession, but that is not necessarily the case . . .

for example, George Clooney only found real fame in his 30s (you can't really count the role as Matt Stevens in 1988's "Return of the Killer Tomatoes!").

And, from an Irish context, there is the example of Brendan Gleeson . . . a schoolteacher who became a star later in life. RADA training will go a long way to honing an actor's skills, but anyone who saw his show-stealing performance in Roddy Doyle's early meisterwork "Brownbread" could see instantly the star potential . . .

even though his "Mr Farrell" is about as far from Shakespeare as one could get. Still, even with this stage experience, he was 35 when he got a film gig in "The Field" (he played a quarryman), and 50 when he played Alastor "Mad Eye" Moody in a Harry Potter Film.

So why would anyone do it?

The answer is fairly obvious . . . the spotlight holds a great allure for many people. But there is also the chameleon nature of a role, where (at least for a time) a person gets to be someone else. Not to mention the occasional fortune that comes with that elusive stardom. It is for these reasons that people will consider themselves an actor first, and whatever other job they are doing second, occasionally to the point of delusion.

And why a lucky few actually get to make a living out of being an actor . . . even if that living is not quite as easy as Hollywood might have led them to believe.

Tom O'Suilleabhain is a good example of a successful Irish actor. His TV and film credits include "On Home Ground", "Paths to Freedom", "The Clinic", "Adam and Paul" and "Showbands".

And he got to shoot Colin Farrell in the Irish hit film "Intermission". Not shoot with. Shoot. But O'Suilleabhan is a good example because, despite the fact that his face is well known, and despite the fact that he is constantly in demand, he is by no means an international film star . . . yet.

His route to acting is your classic accidental success story, whereby a series of coincidences conspired to create his career.

"I was in college for four years, and got a degree in geology, " he said. "And, no, I wasn't into amateur dramatics. But there weren't many jobs for geologists at the time, and I found myself on the dole. I had a friend who was doing a VTOS course in drama in Ringsend, and, when someone dropped out of the course, a place became available, so I just sort of turned up and filled the space."

So his acting career started there?

Not really. O'Suilleabhan's stint in college lasted about six months, where, by his own admission, he was responsible for being asked to leave the course. But he had already done a production of Brecht's Galileo (again, he got the part because somebody dropped out), and that, really, was that.

"I found that I really wanted to act, " he said. "Acting is more like an affliction . . . like getting a disease. After I had done the production, I found other work to be boring and mundane. Acting was like a drug . . . I had to do it."

There followed about three years of social welfare and independent theatre ("profit share productions, where you end up owing them money") . . . but despite the financial hardship, he was "enthused and inspired" over the years. And then he got his first film break, in a film called "On the Edge" by John Carney, writer and director of Bachelor's Walk, and winner of the Audience Award at last year's Sundance Film Festival.

"On the Edge" came about when the budgets for Irish movies were good, and O'Suilleabhan found himself being paid �500 per day, which was a lot for a person on the dole.

"I was sitting in my little dressing room, calculating how much I was making a minute, " he said. "But I was also drawn by the newfound possibility of success and notoriety. I think a lot of people are at that age (late 20s).

Now, however, I would much rather not have any of that notoriety, and I would just like to work as an actor without all the other things that come with it."

Following "On the Edge" came a certain amount of TV and film work . . . although O'Suilleabhan is the first to admit that there were also long periods out of work when he had to take other jobs ("I never lasted more than a week in any of them, " he said). He also learned the value of voiceovers, which he described as a viable way to survive week-in and weekout, in that they allow people the freedom to pursue theatre roles, while giving them the money to travel for auditions.

O'Suilleabhan has now been playing Detective Ronan O'Donoghue on "The Clinic" for three years, so the days of struggling are, at least for the moment, past him. So what has been his favourite role to date?

"I found "Showbands" most enjoyable, and I loved my role as Ricky Duvall in it, " he said. "It was total comedy, with not too many subtleties, which might be why I found the part easy to play. It involved dancing and singing, and, looking at it, I am really proud of what I have done."