Glad you decided to take a look!
Here's a list of everything with Deadpool as the titular character (something i have saved on my computer for moments like this
):
First Appearance: New Mutants #98 by Rob Liefeld and Fabian Nicieza
First Limited Series: Deadpool: The Circle Chase (#1-4), by Fabian Nicieza
First Ongoing Series: Deadpool (1997) (#1-69)
*(#1-33, 0, -1), by Joe Kelly
(#34-45), by Christopher Priest
(#46-55), by Jimmy Palmiotti
(#56), by Buddy Scalera
(#57-64), by Frank Tieri
(#65-69), by Gail Simone
Following this volume of Deadpool, Gail Simone relaunched the title as Agent X, starring Alex Hayden, who was thought to be Deadpool until it was revealed at the end of the series they were separate characters. (#1-15)
Future Ongoing Titles:
Cable and Deadpool (2004) (#1-50), by Fabian Nicieza (#1-48), Reilly Brown (#49, 50)
Deadpool (2008) (#1-63), by Daniel Way
Deadpool Team-Up (2009) (#899-883), by various writers. Counts backwards from one-shot Deadpool #900
Deadpool: Merc with a Mouth (2009) (#1-13), by Victor Gischler
Deadpool Corps (2010) (#1-12), by Victor Gischler
Deadpool (2012) (#1-present), by Gerry Duggan and Brian Posehn, as a part of the Marvel NOW! initiative
Team Titles:
Uncanny X-Force (2008) (#1-35), by Rick Remender
Thunderbolts (2012) (#1-present), by Daniel Way (#1-11), Charles Soule (#12-present)
Additional Limited Series:
Deadpool: Sins of the Past (1994) (#1-4), by Mark Waid
Deadpool: Suicide Kings (2009) (#1-5), by Mike Benson & Adam Glass
Deadpool: Wade Wilson's War (2010) (#1-4), by Duane Swierczynski
Deadpool Pulp (2011) (#1-4), by Mike Benson & Adam Glass
Deadpool Killogy by Cullen Bunn
- Deadpool Kills the Marvel Universe (2012) (#1-4)
- Deadpool Killustrated (2013) (#1-4)
- Deadpool Kills Deadpool (2013) (#1-4)
Night of the Living Deadpool (2014) (#1-4), by Cullen Bunn
Deadpool vs. Carnage (2014) (#1-4), by Cullen Bunn
Deadpool: The Gauntlet (2014) (#1-13), by Gerry Duggan & Brian Posehn *Infinite digital comic*
Deadpool: Dracula's Gauntlet (2014) (#1-7), by Gerry Duggan & Brian Posehn *Converted digital comic to print*
Hawkeye vs. Deadpool (2014) (#0-4), by Gerry Duggan
Deadpool vs. X-Force (2014) (#1-4), by Duane Swierczynski
Deadpool's Art of War (2014) (#1-4), by Peter David
MAX Titles:
Deadpool MAX (#1-12), by David Lapham
Deadpool MAX: Second Cut (#1-6), by David Lapham
One-Shots:
Encyclopedia Deadpoolica (December 1998)
Baby's First Deadpool Book (December 1998)
Deadpool Team-Up (Starring Deadpool and Widdle Wade) (December 1998)
Deadpool/GLI Summer Fun Spectacular (September 2007)
Deadpool: Game$ of Death (May 2009)
Deadpool Corps: Rank and Foul (March 2010)
Lady Deadpool #1 (July 2010)
X-Men Origins: Deadpool #1 (July 2010)
What If: Venom Possessed Deadpool? #1 (February 2011)
Deadpool/Cable #26 (February 2011) (Continued from Cable series that ended with #25)
Deadpool Family #1 (April 2011)
Wolverine/Deadpool: The Decoy #1 (July 2011)
Deadpool MAX X-Mas Special #1 (December 2011)
Deadpool Annual #1 (November 2013)
Deadpool Annual #2 (May 2014)
Deadpool Bi-Annual #1 (September 2014)
I bolded what I believe to be the most "important" runs. Joe Kelly's run in the first on-going is starred because it's undoubtedly the most important of that run. He was the one who started it all. His run can be collected in the Deadpool Joe Kelly omnibus. Cable and Deadpool is my personal favorite ongoing series and that can be collected in trade form. Uncanny X-Force can also be collected in an omnibus.
Daniel Way's Deadpool run... while he had the longest run of any writer on the title to date, it was very up and down. I would say the first three arcs (volumes 1, 2, 3 in trade) and the DEAD (volume 11 I believe) arc are the only ones worth reading.