The name is Robert Gibson.
If there is a name I cannot read – which happens fairly often – then I will turn to what I can read first, and see if that helps to track it down. In this case, given this is an 1899 death certificate, the 1901 Irish census seems a good starting place.
We know his address is 27 Williamstown. So Blackrock area of Dublin. By searching this area I came across:
Robert Gibson, age 34, living in Blackrock, house number 27
You can view the relevant images there to determine whether this is the correct man, but pieces seem to fit. Sometimes to read old documents you need to reverse-engineer until you can work out the original text, which then often becomes obvious. A word of caution, however, to make sure you are not just seeing what you want to see.