Many sitcom characters went by nicknames. What other ones are there?

Beaver
Weezy
Hawkeye
Lumpy
J.J.
Buffy
Tootie

John-Boy
Jim-Bob
Potsie
Fonzie
Radar

Wojo

Boss Hogg

Manly Wilder

Trapper John

Hot Lips

Ferret Face
Mr Big
The Big RAGU
Gopher
Dr Robert "Rocket" Romano on ER
Red Foreman
The Skipper and the Professor
Meathead
Gonzo Gates from Trapper John MD

beloved "Coach" on Cheers
on Entourage
"E"
"Turtle"
"Drama"

Dauber on Coach

Charles "Chachi" Arcola - Happy Days
Burl "Gopher" Smith - The Love Boat
Adam "Doc" Bricker - The Love Boat
Freddie "Rerun" Stubbs -What's Happening
Roger "Rog" Thomas - What's Happening
Buddons "Buddy" Lembeck - Charles in Charge
Maurice "Buddy" Sorrell - The Dick Van Dyke Show
Irwin "Skippy" Handleman - Family Ties
Carmine "The Big Ragu" Ragusa -Laverne and Shirley
Andrew "Squiggy" Squiggman - Laverne and Shirley

Samuel "Screech" Powers on Saved by the Bell

Richard "Boner" Stabone - Growing Pains
Freddie "Boom Boom" Washington - Welcome Back Kotter
Clarence "Lumpy" Rutherford - Leave it to Beaver
Montgomery "Scotty" Scott - Star Trek
Leonard "Bones" McCoy - Star Trek

Will on "Fresh Prince" had funny nick names for everyone, like "G", "C" and "Hil". Not to mention his friends Jazz, Ice Tray and Ty.

DJ on Full House... her real name is Donna Jo Margaret, but she was always called DJ.

The Skipper

The Professor

Poppo, Cool Breeze and Head (JJ's buddies on Good Times)

Stanley "Wojo" Wojohowicz - Barney Miller
Bob "Bulldog" Briscoe - Frasier
Jefferson Davis "Boss" Hogg - Dukes of Hazzard
Douglas "Doogie" Howser - Doogie Howser M.D.
Frank "Ponch" Poncherello - CHiPS
Charmaine "Schultzy" Schultz - The Bob Cummings Show
Regina "Reggie" Kostas - Becker
George "Kingfish" Stevens - Amos and Andy
Florence Jean "Flo" Castleberry - Alice/Flo

Isabelle "Belle" Dupree - Alice

Agent 99 (we never did find out her real name) - Get Smart

Leticia "Buddy" Lawrence - Family