Following the show's panel at Comic-Con International, Syfy released the first teaser trailer for the Christopher Meloni-led Happy! based on the comic of the same title.RELATED: Happy: TV Adaptation of Morrison & Robertson’s Comic Gets Series Order.The trailer comes after it was revealed that actor Patton Oswalt has stepped in to voice the title character, replacing Saturday Night Live actor Bobby Moynihan who voiced the character in the pilot. Oswalt is one of two castings on the series in the past week, with Money Monster’s Joseph Reitman confirmed to join the series just yesterday as a “crazy and delusional” central villain.

RELATED: Syfy’s Happy! Finds Its Smoothie in Lost Alum.

Here’s the network’s official series description: “The series follows Nick Sax (Christopher Meloni, “Law & Order: SVU”) – an intoxicated, corrupt ex-cop turned hit man – who is adrift in a world of casual murder, soulless sex and betrayal. After a hit gone wrong, his inebriated life is forever changed by a tiny, relentlessly positive, imaginary blue winged horse named “Happy."'

Joining Meloni, Moynihan and Reitman in the series are Patrick Fischler (Lost, Mad Men), who is set to play Smoothie, Ritchie Coster (Blackhat) who is set to play Mr. Blue aka Leonardo Scaramucci, and actress Zabryna Guevara (Gotham), who will play the beleaguered single mom Amanda Hansen.

The pilot episode was written by Grant Morrison and Crank writer-director Brian Taylor, with Taylor also stepping behind the camera to direct. Morrison, Taylor and Meloni all serve as executive producers, along with Neal Moritz, Pavun Shetty and Toby Jaffe of Original Film, and showrunner Patrick Macmanus.

A premiere date has not been set for the series, although it will debut on the network sometime this Fall.