I will have up to 20 shows per letter. Like on epguides.com, shows starting with the or a will be counted as first letter of their second word.

A
1. The Andy Griffith Show
2. The American Bible Challenge
3. Alaska Daily
4. Adam-12
5. The Alfred Hitchcock Hour/Alfred Hitchcock Presents
6. Accused (US)
7. Atlantis
8. The Addams Family
9. All Creatures Great and Small (2020)
10. Around the World in 80 Days (2021)
11. Almost Paradise
12. ALF
13. Awake
14. America Says
15. As Time Goes By
16. The Adventures of Ozzie and Harriet
17. According to Jim
18. Are You Being Served?
19, Angie
20. APB

B
1. Benson
2. Barney Miller
3. The Beverly Hillbillies
4. Blue Bloods
5. Boy Meets World
6. Bachelor Father
7. Bewitched
8. Believe
9. Beyond Belief: Fact or Fiction?
10. BrainDead
11. Back to You
12. Blockbusters (Bill Cullen)
13. The Bob Newhart Show
14. Blossom
15. The Big Bang Theory
16. Big Sky
17. Beyond
18. Beat the Bridge
19. The Brady Bunch
20. The Brady Brides

C
1. Columbo
2. Corner Gas
3. Coach
4. Castle
5. The Chase (GSN)
6. Classic Concentration (Alex Trebek)
7. College Bowl (Peyton Manning)
8. Cheers
9. Cash Cab (Ben Bailey- Discovery)
10. The Chosen
11. Charlie's Angels (1976)
12. The Cosby Show
13. The Courtship of Eddie's Father
14. CSI: Cyber
15. Christy
16. Corner Gas Animated
17. C.P.O. Sharkey
18. Candid Camera- 1998 and 2014 versions
19. The Closer (TNT)
20. Chain Reaction (Dylan Lane)

D- first letter that comes up short of 20 (and short of 15 even)
1. Designated Survivor (ABC seasons only)
2. Dragnet (1967)
3. The Dick Van Dyke Show
4. Diagnosis Murder
5. Dragnet (1951)
6. Diff'rent Strokes
7. DAG (2000)
8. Dispatches from Elsewhere
9. Double Dare (Alex Trebek)
10. A Different World
11. The District
12. The Doris Day Show
13. Dogs in the City

E- even weaker than D was, except for the very top
1. Early Edition- still my #1 show of all time
2. East New York
3. Everybody Loves Raymond
4. Eight is Enough
5. 8 Simple Rules for Dating my Teenage Daughter
6. Emergency!
7. Emergence
8. The Ed Sullivan Show- This classic might be higher up if full unedited episodes were available, all I have seen are best of airings on Decades. :(
9. Extreme Cheapskates
10. 800 Words
11. Ed

F
1. Fame
2. Frasier (1993)
3. 500 Questions
4. Fawlty Towers
5. Family Affair (1966)
6. Family Ties
7. The Facts of Life
8. For the People (2018)
9. Family Feud (John O'Hurley)
10. Family Feud (Richard Karn)
11. FBI (2018)
12. FBI: Most Wanted
13. Found
14. Friends (1994) (There was a flop from 1979 also called Friends, only lasted 5 episodes on ABC. :lol:)
15. Fish
16. Family Matters
17. Frequency
18. FBI: International
19. Flip Side
20. Fam

G
1. Grand Slam (GSN)
2. Gilmore Girls
3. Granite Flats
4. Greed
5. Gomer Pyle, U.S.M.C.
6. George Lopez
7. Growing Pains
8. The Greatest American Hero
9. The Guardian
10. Green Acres
11. Grease: You're the One that I Want!
12. Genius (Einstein season)
13. The George Burns and Gracie Allen Show
14. Gilligan's Island
15. The Good Doctor
16. Genius Junior
17. Grace Under Fire
18. Ghosts (US)
19. Gidget
20. Good Sam

H
1. Hostages (2013)
2. Highway Patrol
3. Home Improvement
4. Heartland (Canada)
5. Head of the Class (1986)
6. Happy Days
7. Highway to Heaven
8. Hope and Faith
9. Hazel
10. Hudson and Rex
11. Hart to Hart
12. Hawaii Five-O (1968)
13. Hollywood Squares (Tom Bergeron)
14. Happy's Place
15. High Potential

I
1. I Love Lucy
2. I Dream of Jeannie
3. It's a Living
4. The Irrational
5. I'm With Her

J
1. The Jack Benny Program
2. The Jeffersons
3. Justice (2006)
4. Joan of Arcadia
5. Jeopardy! (Alex Trebek)
6. Jeopardy! (Ken Jennings as host)
7. The Jay Leno Show
8. Jericho (2006)
9. Jeopardy! (Mayim Bialik)
10. The Jeff Foxworthy Show
11. Judge Judy

K
1. The Kids Are Alright
2. Kevin (Probably) Saves the World
3. Kraft Suspense Theatre
4. Knight Rider (1982)
5. Keeping Up Appearances

L
1. Leverage (TNT only)
2. Law and Order
3. The Lucy-Desi Comedy Hour
4. Lincoln Heights
5. The Lone Gunmen
6. The Love Boat
7. Leave it to Beaver (1957)
8. Lou Grant
9. Law and Order: Criminal Intent
10. Law and Order: Trial by Jury
11. The Law and Harry McGraw
12. The Lucy Show
13. Laverne and Shirley
14. Life with Bonnie
15. Leonardo
16. Life Unexpected
17. Limitless
18. Life is Wild
19. Lincoln Rhyme: Hunt for the Bone Collector
20. Lingo (Chuck Woolery)

M- what a loaded letter
1. Mad About You (1992)
2. The Middle
3. M*A*S*H
4. Murphy Brown (1988)
5. Mental Samurai
6. Manifest
7. Matlock (Andy Griffith version only)
8. Major Crimes
9. The Mary Tyler Moore Show
10. Monk
11. My Two Dads
12. The Munsters
13. Mr. Belvedere
14. Make It or Break It
15. Million Dollar Password
16. Merv Griffin's Crosswords
17. Mork and Mindy
18. Man With a Plan
19. Murder, She Wrote
20. MacGyver (1985)

N
1. Newhart
2. Night Court (1984)
3. NCIS
4. The Nanny
5. No Ordinary Family
6. The Neighborhood
7. 9-1-1
8. Necessary Roughness
9. Now You See It (Jack Narz)
10. NCIS: Origins

O
1. $100,000 Pyramid (Dick Clark)
2. Once Upon a Time
3. Once Upon a Time in Wonderland
4. One Day at a Time (1975)
5. Outrageous 911
6. Our House
7. The Odd Couple (1970)
8. Only Murders in the Building
9. 1 vs. 100 (Bob Saget)
10. The 1% Club
11. Outmatched

P
1. Petticoat Junction
2. The Practice (1997)
3. Psych
4. Prodigal Son
5. People Puzzler
6. Punky Brewster (1984)
7. Perry Mason (Raymond Burr versions only)
8. The Patty Duke Show
9. Person, Place, or Thing
10. Privileged
11. Party of Five (1994)
12. Promised Land (1996)
13. Password Plus (Allen Ludden)
14. The Partridge Family
15. Proven Innocent
16. Password (Allen Ludden)
17. Perception
18. Password (Keke Palmer)

Q
1. Quantum Leap (1989)
2. Quantum Leap (2022)

R
1. Rizzoli and Isles
2. Resurrection
3. Rags to Riches
4. Reba
5. The Rockford Files
6. Rebel (2021)
7. Rich Man, Poor Man- Book I
8. Raising Hope
9. The Real McCoys
10. Ruby and the Rockits
11. Richard Simmons' Dream Maker
12. The Rookie: Feds
13. Reef Break

S
1. Star Trek: Deep Space Nine
2. Some Mothers Do 'Ave 'Em
3. Supermarket Sweep (David Ruprecht)
4. Scorpion
5. Star Trek: the Next Generation
6. 7th Heaven
7. Seinfeld
8. Switched at Birth
9. Sabrina, the Teenage Witch
10. Split Second (Monty Hall)
11. Split Second (John Michael Higgins)
12. The Spencer Sisters
13. Superhuman
14. Sister, Sister
15. S.W.A.T. (2017)
16. Star Trek: Voyager
17. Step by Step
18. Super Password
19. Speechless
20. Suits

T
1. $25,000 Pyramid (Dick Clark)
2. Touched by an Angel
3. Touch
4. 3rd Rock from the Sun
5. That Girl
6. Too Close for Comfort
7. The Twilight Zone (1959)
8. Taxi
9. The Thing About Pam
10. Trivial Pursuit (LeVar Burton)
11. 20Q
12. Timeless
13. The Tonight Show Starring Johnny Carson
14. The Tonight Show with Jay Leno
15. Tracker
16. Tug of Words (Samantha Harris)
17. $25,000 Pyramid (Bill Cullen)
18. Ties That Bind
19. Trivia Trap
20. 25 Words or Less

U
1. Under the Dome
2. United States of Al

V
1. Vegas (2012)

W
1. WKRP in Cincinnati
2. Wings (1990)
3. The Waltons
4. The Wonder Years (1988)
5. Without a Trace
6. Welcome Back, Kotter
7. The Weakest Link (Anne Robinson US)
8. Weakest Link (Jane Lynch)
9. Wind at My Back
10. White Collar (2009)
11. Win Ben Stein's Money
12. Who Wants to be a Millionaire? (Regis Philbin)
13. Wheel of Fortune (Pat Sajak)
14. Who's the Boss? (1984)
15. Wild Cards
16. Wild at Heart
17. What's My Line? (John Daly)
18. What a Country!
19. Wayward Pines
20. The Wizard of Paws

X
1. The X-Files

Y
1. Yes, Minister/Yes, Prime Minister
2. Young Sheldon
3. You Bet Your Life with Jay Leno

Z
1. Zoey's Extraordinary Playlist
2. Zoo (2015)

A - Ally McBeal
B - Babylon 5
C - The Conners
D - Deadwood
E - Everwood
F - Frasier
G - Gilmore Girls
H - Hill Street Blues
I - I Love Lucy
J - Justified
K -
L - L.A. Law
M - Mom
N - The Nanny
O - Once Upon a Time
P - Picket Fences
Q - Questo Mondo Non Mi Renderà Cattivo
R - Roseanne
S - Spin City
T - Twin Peaks
U - Unhappily Ever After
V -
W - The Wire
X - The X-Files
Y -
Z - Zoey's Extraordinary Playlist

All in the Family (runner up: Alice, 2nd runner up: ALF)
Buffy the Vampire Slayer
Courtship of Eddie's Father
Dark Shadows
Emergency
Flintstones
Gilligan's Island
Highway Patrol
I Love Lucy
Jeopardy!
Kolchak
Laverne & Shirley
Mr. Ed (runner up: Munsters)
Newlywed Game
Ozzie & Harriet
Petticoat Junction
Quincy
Rockford Files
Seinfeld
That Girl
Untouchables
Voyage to the Bottom of the Sea
Welcome Back Kotter
X-Files
Yellow Rose
Zig & Sharko

I hope Trivial Pursuit has a very long run on the CW. It has made the top half of the Ts.