From The TV IV
Neil is one of the Oceanic 815 crash survivors on the mysterious island. He is known to many of the other survivors as "Frogurt". He is played by Sean Whalen and appeared in four episodes and one mobisode.
Before Oceanic 815
Not much is known about Neil's life before the crash, except for the fact that he used to sell frozen yogurt. This is where his nickname "Frogurt" came from.
After the crash
Neil hasn't done much on the island since the crash. He did however have a crush on Libby after she joined the main beach camp. He became jealous of Hurley, who was spending quite a lot of time with Libby. He confronted Hurley and asked him what was going on with him and Libby. To Neil's surprize, Hurley was on his way to have a date with Libby. However, Michael Dawson killed Libby before their date became a reality.