Re: Help! Skills Outside of the Core Books
 

IME, most of the wholly new skills are fairly niche: Imbuement skills in Power-Ups 1: Imbuements, Power skills in Psionic Powers, etc. New and revised specialties pop up all over the place, but are often (but not always) setting- or genre-specific*; plus, they can end up buried in side-boxes, such as Guns (Wrist Gun) getting buried in a side-box in High-Tech.

GURPS being a toolkit, it's entirely possible to alter the skills (see Power-Ups 10: Skill Trees for a total rework) for your campaign. I've done so several times, mostly in my space opera games (a lot of the changes I made in my custom space opera setting's skill list were tested nearly a decade and a half ago in a Star Wars game, when all I had was the Basic Set and Ultra-Tech).



* I'm actually surprised Driving (Hovercycle), distinct from Driving (Hovercraft), hasn't shown up in an official book or Pyramid article yet, tbh.

Re: Help! Skills Outside of the Core Books
 

There's an index to the Skill of the Week series of postings here.

Re: Help! Skills Outside of the Core Books
 

Three sources which at least aspire to being complete lists below. I can't vouch for the completeness or correctness of any of them. (Not solely because I'm lazy, but also because I don't have all the published GURPS books, much less all the Pyramids.)

https://gurps.fandom.com/wiki/List_of_Skills
https://gurpsland.no-ip.org/pdf/Comp...phabetical.pdf
http://gurpswiki.wikidot.com/ind:skills

Re: Help! Skills Outside of the Core Books
 

If you download GCS Gurps Character Sheet), the libraries have a decent amount of listings for skills, that usually give a book and page reference to learn more

Re: Help! Skills Outside of the Core Books
 

What Dagothdoom said. GCS has a large compilation of skills, advantages, equipment, notes, rule links, etc.