MTV (Music Television; see also MTV's Oddities and The 10 Spot)
(launched in 1981)
IMDb; official website; TV Tropes; Wikipedia

MTV Video Music Awards (9/14/1984 - present)
120 Minutes (3/10/1986 - ?/?/2000; aired on MTV2, 2001-2003, with a revival in 2011-2013)
Aeon Flux (11/30/1991 - 10/10/1995)
MTV Movie Awards (6/10/1992 - present; in 2017 its name changed to MTV Movie & TV Awards)
Beavis and Butt-Head (9/22/1992 - 11/28/1997; I didn't see much of this, and none of the 2011 revival)
Squirt TV (1994-1995)
The Maxx (4/8/1995 - 6/19/1995)
Idiot Savants (12/9/1996 - 4/25/1997)
Daria (3/3/1997 - 6/25/2001)
Oddville, MTV (6/16/1997 - ?/?/1999)
Apt. 2F (7/13/1997 - 10/7/1997)
Sifl 'n' Olly (1997-1999)
Celebrity Deathmatch (1/1/1998 - 6/6/2002; s5-6 aired on MTV2)
Downtown (8/3/1999 - 11/8/1999)
Spy Groove (? - ?; originally aired for 13 episodes on Teletoon in Canada, only 6 of which aired on MTV)
Is It Fall Yet? (8/27/2000; TV movie)
Undergrads (4/1/2001 - 8/12/2001)
Is It College Yet? (1/21/2002; TV movie)
Clone High (1/20/2003 - 3/10/1993; originally aired on Teletoon in Canada for 13 episodes, only 8 of which aired on MTV)
Spider-Man: The New Animated Series (7/11/2003 - 9/12/2003)
Monster Island (3/7/2004)
Teen Wolf (6/5/2011 - 9/24/2017; I watched at least part of season 1, but didn't have the chance to see any more of it)

stuff I want to see
Dead at 21
The Head
My Super Psycho Sweet 16 (TV movie)

MTV2
(launched in 1996 as M2; renamed MTV2 in 1999)
Subterranean (2003 - 2011)
Wonder Showzen (3/11/2005 - 5/19/2006)
The Andy Milonakis Show (6/26/2005 - 5/1/2007)