Singapore-born Dr John Climax (67) co-founded one of the world's biggest clinical trial companies, Icon Pharmaceuticals with fellow Rich Lister Ronan Lambe. It currently employs 13,000 people in 38 countries.
He's believed to retain a stake of 2.2pc - worth about €146m - in the Nasdaq-listed business, which floated in 1998 and is now valued at over $7.5bn. The shares had a good year in 2018, and are up by about 25pc.
The Foxrock-based entrepreneur sold about €70m worth of shares when he stepped down as CEO in 2009, having banked salaries over the years of more than €15m, but he has a second company, DS Biopharma that is focused on developing treatments for dermatitis and other skin conditions, also co-founded with Lambe. A firm that was spun out in 2016, Afimmune booked a €12m loss in 2017.