So I was thinking that Mr. Howell's name didn't sound right, so I started Googling around a bit. I was right, after I was wrong, that is: it wasn't P. Was it J.? Thurston J. Howell III.? Or just Thurston Howell?
But then I found out that Mrs. Howell's name is Eunice Wentworth. The Skipper was Jonas Grumby. Gilligan was his last name, and his first name was Willie, although--
>>>ATTENTION SPOILER ALERT<<<
in the 1996 movie, A Very Brady Sequel, [screenplay by Sherwood Schwartz, who produced both series], there's a character named Dr. Whitehead [played by John Hillerman (1)] whose son Gilligan was lost at sea.
Gilligan was on a boat with Carol Brady's first husband, Roy. The Professor. 
How could this vital piece of information--even though it was a blatant attempt to cash in on 70's-era TV nostalgia--have slipped by me?
Gilligan's Island [wikipedia]
 Higgins' full name: Jonathan Quayle Higgins III 
 except that Brady's husband was Roy Martin, and the Professor was Roy Hinkley. But still.
 Not only did Higgins get sideswiped by having the middle name Quayle before Dan Quayle ruined it, In season 2, he had a half-brother, a rodeo cowboy, named Elmo Ziller.