
My introduction to the character actually took place in the pages of Suicide Squad #1, which I picked up because of the "Legends" crossover blurb on the cover.
This series though, by Ostrander, Yale and McDonnell, took Floyd Lawton's character which they'd been building in the main title and cemented it. The four issue mini-series was a perfect exploration of the character's history and motivations.
For me, and the way the selective continuity in my brain works, the original 1988 Deadshot mini-series is on par with, and DC's answer to, Marvel's original Wolverine mini from Claremont and Miller.
As far as I know, the series has never been collected but if you can find the issues is the dollar bins grab them. You won't be sorry.
Oh, and remember "DC Comics aren't just for kids", in case you needed that reminder while reading a story about a suicidal contract killer with mother issues who dresses up in orange and silver tights.