Season two of "Marvel's Agents of S.H.I.E.L.D." continues to take shape with two new cast additions announced on Thursday. Marvel.com has official word that Henry Simmons has been cast in the recurring role of "Alphonso 'Mack' Mackenzie," a "mechanic in his 30s" allied with Coulson (Clark Gregg)'s team. The character is based on Marvel Comics character Alphonso Mackenzie, a S.H.I.E.L.D. agent introduced by Bob Harras and Paul Neary in 1988's "Nick Fury vs. S.H.I.E.L.D." #3.

Additionally, Entertainment Weekly reports that Kyle MacLachlan has been cast in the key role of Skye (Chloe Bennet)'s father, though Marvel has yet to confirm. Skye's true history became an open question when she was revealed to be an "0-8-4" ("object of unknown origin"), and remained unresolved by the finale -- though a mysterious (and apparently not quite human) character was handed a photo of Skye and told his daughter has been found in one of the final scenes of the first season.

This marks a return for both actors to one-hour dramas on ABC. Simmons played Det. Baldwin Jones on "NYPD Blue" for five years, and MacLachlan is well known for both his lead role in "Twin Peaks" and his supporting role in "Desperate Housewives."

The second season of "Marvel's Agents of S.H.I.E.L.D." is set to debut at 9 p.m. Tuesday, Sept. 23 on ABC.