The eighth member of the PAW Patrol is Mighty Pups character Cap'n Turbot, although the most commonly recognized eighth member is Everest, a husky who specializes in winter rescues. Everest became an official member of the PAW Patrol in the episode "The New Pup."
If you're referring specifically to the Mighty Pups version of the team, there might be different versions and characters introduced in various episodes or spin-off media. Please let me know if you need details about a specific version or aspect of the PAW Patrol!