This being the 25th anniversary of Nick at Nite, here's a complete list of every show to ever air regularly on Nick at Nite.

1. Dennis The Menace
2. The Donna Reed Show
3. Nick at Nite Movie
4. Turkey Television
5. Route 66
6. National Geographic Explorer
7. My Three Sons
8. Mister Ed
9. I Spy
10. The Smothers Brothers Show
11. The Monkees (aired 1986-1988 before returning briefly in 1997)
12. The Ann Sothern Show
13. Private Secretary
14. The Bad News Bears
15. Mad Movies with the L.A. Connection
16. Car 54, Where Are You?
17. Rowan & Martin's Laugh-In
18. The Golden Age of Television (Sundays in November 1987)
19. The Danny Thomas Show
20. Lancelot Link: Secret Chimp
21. Saturday Night Live
22. SCTV Network 90
23. The Patty Duke Show
24. The Smothers Brothers Comedy Hour
25. On the Television (special aired April 1989, regular series began 1990)
26. Looney Tunes (separate Nick at Nite airings from Nickelodeon daytime)
27. Bewitched (first aired 1989-1992, and again 1994-2000)
28. Lassie
29. Green Acres (returned briefly in 1996 and 1997 while airing on TV Land)
30. The Many Loves of Dobie Gillis
31. Fernwood 2-Night
32. Alfred Hitchcock Presents
33. Dragnet
34. Get Smart
35. Mork & Mindy
36. Hi Honey, I'm Home
37. The Adventures of Superman
38. The Dick Van Dyke Show
39. F Troop
40. The Lucy Show
41. The Mary Tyler Moore Show
42. The Partridge Family
43. The Bob Newhart Show
44. I Dream of Jeannie
45. The Lucy-Desi Comedy Hour
46. The White Shadow (aired 1994-1996 before moving to TV Land)
47. Taxi
48. Welcome Back, Kotter
49. The Munsters
50. Gilligan's Island (1995-2000 Australia, USA 2000-2001)
51. The Courtship of Eddie's Father (Australia only)
52. The Jim Nabors Hour (Australia only)
53. The Fugitive (Australia only)
54. The Prisoner (Australia only)
55. Fireball XL-5 (Australia only)
56. The Addams Family (Australia 1995-2001, L.A. 2006-, USA 1996-1997)
57. Flash Gordon (Australia only)
58. Bonanza (Australia only)
59. Peter Gunn (Australia only)
60. Flipper
61. Petticoat Junction (Saturdays from May-July 1996 in TV Land preview)
62. St. Elsewhere (Saturdays from May-July 1996 in TV Land preview)
63. Hill Street Blues (Saturdays from May-July 1996 in TV Land preview)
64. Cannon (Saturdays from May-July 1996 in TV Land preview)
65. That Girl (Sundays on Nick at Nite in May 1996)
66. Rhoda
67. Phyllis
68. The Betty White Show
69. The Odd Couple
70. Happy Days (1996-2000, returned 2002-2003 while airing on TV Land)
71. Newhart
72. Doogie Howser, M.D. (UK only)
73. Wortzel Gummage (UK only)
74. Mr. Bean (UK only)
75. The Wonder Years
76. The Brady Bunch (Acquired in 1998, though aired as specials in 1995)
77. Laverne & Shirley
78. All in the Family (week-long salute October 1998, regular 2000-2004)
79. The Jeffersons
80. WKRP in Cincinnati
81. The Beverly Hillbillies
82. The Facts of Life
83. Roseanne (acquired in 2000, aired regularly 2003-2009)
84. Full House (acquired in 2000, aired regularly 2003-2009)
85. Diff'rent Strokes
86. Silver Spoons (aired Sundays as part of Totally '80s Sunday)
87. ALF (aired Sundays as part of Totally '80s Sunday)
88. 227 (aired Sundays as part of Totally '80s Sunday)
89. Family Ties
90. Cheers
91. Kids Say the Darndest Things (first seen late 2001, regular 2002-2005)
92. The Cosby Show
93. Charles in Charge (CBS 1984-1985 episodes not included)
94. Coach (1994-1997 episodes not included)
95. Perfect Strangers (first seen in 2000, aired regularly in 2003)
96. Head of the Class (first seen in 2000, aired regularly in 2003)
97. Wings
98. Who's the Boss? (acquired in 2003, aired regularly from 2004-2006)
99. The Fresh Prince of Bel-Air (acquired in 2003, aired regularly 2004-2009)
100. Murphy Brown (acquired May 2004, aired regularly 2005-2008)
101. Home Improvement (acquired August 2004, aired regularly 2007-2009)
102. Mad About You (acquired August 2004, aired regularly 2006-2008)
103. The Nanny (acquired August 2004, aired regularly since 2009)
104. Friends (acquired May 2005, will begin airing Fall 2011 on Nick at Nite)
105. Growing Pains (first seen June 2005, aired regularly 2007-2008)
106. NewsRadio
107. A Different World
108. Family Matters (acquired December 2006, aired since June 2008)
109. America's Funniest Home Videos (1989-1994 Bob Saget episodes only)
110. The George Lopez Show
111. Everybody Hates Chris (acquired March 2008, aired since Fall 2009)
112. Malcolm in the Middle
113. Glenn Martin, DDS
114. My Wife and Kids
115. The Persuaders (UK only)
116. Three's Company (Thanks Pavan for realizing I'd neglected to mention that)
117. The Andy Griffith Show (aired weekends 2000-2001, also seen weekdays on TV Land)

For the record, there WAS indeed a Nick at Nite UK seen in Torquay, England in the mid 1990s, and here are several instances of proof:

http://www.youtube.com/watch?v=sH5_EgiGfIc

http://www.youtube.com/watch?v=78MJhKnaYl8

http://www.youtube.com/watch?v=2grrdXEfdEE&feature=related

http://www.youtube.com/watch?v=FL0yzLv3eD8

Three's Company?