Sacco

Saffron

Sailor

Saint

Salerno

Salsa

Salt

Saltie Dog

Salty

Sam I Am

Sambo

Sambuco

Sami

Samori

Sanders

Santa

Santa's Little Helper

Sappho

Saturn

Saxton

Scamp

Scamper

Scampi

Scardey

Scare

Scaredy

Scaredy Cat

Schizo

Schnee

Schnitzel

Schnitzy

Schooner

Schrodinger

Schwartz

Schwazili

Scissors

Sco

Scone

Scooter

Scorpio

Scotch & Soda

Scoundrel

Scout

Scrappy

Scratch

Scrawny

Scrawny Cat

Screamer

Screech

Screwtop

Scruff

Scruffy

Scud

Scudder

Scully

Scuzzface

Seabone

Seamore

Seetay

Seltzer

Seminole

Senator

Senior

Sepher

Set

Seven

Shadow

Shady

Shaft

Shakes

Sham

Shaman

Shammy

Shamrock

Shamus

Shandy

Shanghi

Sharky

Shatzie

Shay

Shaynmeister

Shazbot

Shazzam

Sheeber

Sherlock

Sherlock Holmes

Sherlocke and Watson

Shiloh

Shimmer

Shine

Shino

Shiraz

Shiriki

Shirin

Shish

Shit

Shitakii

Shitani

Shitty Kitty

Shmoo

Shoobbie

Shoogar

Shortie

Shortstop

Shorttail

Shosh

Shotzie

Shovel

Shrambles

Shut Up

Shy One

Sid

Sid Vicious

Sidmeister

Sigurd

Silver

Silverstein

Silvie

Simkin

Simpatico

Sin

Sinatra

Sinbad

Sine

Skanky

Skeet

Skeeter

Skids

Skipper

Skippy

Skittah

Skitter

Skittles

Skookum

Skor

Skoshi

Skrawny

Skunk

Skunky

Skweeter

Sky

Skyler

Skymble

Slash

Slasher

Slate

Sleek

Slick

Slickers

Slicks

Slim

Slinkerdoodle

Slinkus

Slinky

Slinx

Slither

Slither Cat Slug

Sluggo

Slurp

Sly

Smack

Smedly

Smeghammer

Smidgen

Smidget

Smidgewidge

Smiley

Smither

Smitty

Smog

Smoke

Smokey

Smokie

Smoky

Smoochers

Smoochie

Smoogee

Smudge

Snaggle

Snakers

Snapshot

Sneakers

Sneaky Joe

Snickers

Sniff

Snit

Snitch

Snook

Snooker

Snookie

Snookster

Snookums

Snooky

Snooky Wooky

Snooper

Snoopy

Snorky

Snotje

Snots

Snow

Snowball

Snowflake

Snowman

Snowshoe

Snowstorm

Snowy

Snuggles

Socks

Soda

Sofa

Sonny

Sonta

Sony

Soo-Soo

Sook

Soosh

Sooti

Sootico

Sootikin

Sooty

Sopher

Soran

Sorceror

Souki

Soul

Soup

Sox

Spacey

Spanky

Spare Parts

Sparky

Sparti

Spats

Spaz

Special

Speck

Specter

Spectro

Speed

Speedy

Spenser

Spider

Spidey

Spiff

Spike

Spikey

Spinoza

Spirit

Spitfire

Spitsey

Spitz

Spitzette

Splash

Splat

Spliff

Splinter

Splotch

Splotches

Spock

Spokane

Spoofy

Spooge

Spook

Spookie

Spookins

Spooky

Sport

Spot

SpotHead

Spots

Spotty

Spotzilla

Spring

Sprinkale

Sprinkales

Sprite

Sprocket

Sprout

Spud

Spudnik

Spunkie

Spunky

Spur

Sputnik

Sputz

Sputza

Spyder

Squeak

Squeaker

Squeakers

Squeaks

Squeeks

Squeeky

Squeeler

Squidge

Squiffel

Squirm

Squirrel

Squirt

Squishy

Sqwert

Stag

Stank

Star

Starbuck

Starsky

Stash

Stavanger

Stealth

Steinway

Steve O

Stevenstien

Steverino

Stevers

Steverspoo

Stevester

Stevie Wonder

Stick

Stiltcat

Stimpy

Stinky

Stinkybutt

Stitch

Stitchery

Stitches

Stolen

Stonewall

Stop That!

Stopper

Storm

Storm Cloud

Stormie

Stormy

Stranger

Stranger Danger

Stranger Ranger

Stranger Than Most

Strepe

Stress

Stretch

Stribe

Strider

Striker

Stripington

Stroker

Strutter

Stryper

Stubby

Stubie Wubbie

Stubman

Studley

Stump

Stumpy

Stupid

Stymie

Succotash

Sultan

Sulu

Sundance

Sundown

Sunnyboy

Sven

Swee-Pee

Sweep

Swoozie

Sy

Sylmony

Sylvin

Symba