Sorry, but there are many more than four for me. I'm most inspired day-to-day by the participants in the Seasons of the Ukulele contests. Viva las Seasonistas!!
As for famous uke players, I love Eddie Kamae, Herb Ohta, May Singhi Breen, and Cliff Edwards.
IZs somewhere over the rainbow is what got me started but my favorite players now are
1. James hill
2. kalei gamiao
3. Jake shomabukuro
4. Aldrine guerrero
Iz and Rainbow for introducing my to the instrument as a real instrument.
Jake because everytime someone makes a Tiny Tim reference I just play one of his YouTube videos and they shut up.
Eddie Veder because I've always loved Pearl Jam and his music.
Aldrine for all of his awesome lessons online.
Alternates would be James Hill because he is as awesmoe as Jake although very different.
Jim Beloff for his great books that were my first books I learned from.
My father, not much of a uke player, much better guitarist, but for passing on a love of music and stringed instruments to me.
I don't look for or listen to "professional" ukulele players so I can't say there are any players who currently inspire me to play the ukulele. The players who inspired (past tense) me to seek out the ukulele and start playing were all casual players who looked like they were having a lot of fun playing. I don't think any of them are necessarily seeking to be great players but seemed to be in it for the fun.
William H. Macy
Kate Micucci
Tony Danza
Zoey Deschanel
I think I saw all of them play a uke on TV in the span of 1 or 2 years and it piqued my curiosity to the point of wanting to try and then actually buying a ukulele.
Ooops! I forgot George Harrison. He can have Tony Danza's spot! :^D