For much of his early career Patrick excelled at playing villains and bad guys as in his screen debut as a psycho biker in "Warlords from Hell" (1987). He spun his wheels for awhile as another psycho in "Equalizer 2000" and as soldier Johnny Ransom in "Eye of the Eagle" (both 1987), as an ex-Marine in "Future Hunters" and again as Ransom in "Behind Enemy Lines" (both 1988). His first high profile baddie was as a terrorist in the sequel "Die Hard 2: Die Harder" (1990).

The next year, Patrick landed the star-making role as the shape-shifting cyborg death machine T-1000 in James Cameron's "Terminator 2: Judgment Day" (1991). While on the surface, the role did not seem to require much effort, the actor lent the appropriate air of menace and terror to the part and he proved an effective foil to Arnold Schwarzenegger. But despite that high profile success, Patrick was unable (or unwilling) to make the jump to the A-list. He was back to appearing in such low-budget fare as "Body Shot" and "The Cool Surface" (both 1994) and "The Last Gasp" (1995). He did spoof his "T2" persona as a bad cop in the hit comedy "Wayne's World" (1992) and reprised the part in a cameo in the Schwarzenegger vehicle "The Last Action Hero" (1993). That same year, he did what he could portraying the concerned best friend of man (D B Sweeney) who disappeared and later claims to have been abducted by aliens in "Fire in the Sky". In the equally improbably "Double Dragon", the actor appeared to be having some fun as a futuristic, silver-maned warlord. Patrick proved fine as Demi Moore's psycho ex-husband in "Striptease" (1996) and joined the all-star cast of James Mangold's "Cop Land" (1997) as Harvey Keitel's right hand man.

In 1996, Patrick formed his own production company, 360 Entertainment and produced a pair of horror thrillers that eventually aired on The Sci-Fi Channel: "Within the Rock" (1996), following a team of miners who accidentally release an alien and featuring his wife Barbara; and "Ravager" (1997), about a group of scientists stranded in a remote area who are exposed to a deadly chemical. As a performer, Patrick continued to rack up credits in several low-budget generically-titled features that ended up on cable like "Tactical Assault" and "Renegade Force" (both 1998). He made an impression in his brief role as the football coach in "The Faculty" (also 1998) and headlined the direct-to-video sequel "From Dusk Till Dawn 2: Texas Blood Money" (1999).

At the dawn of the new millennium, the actor's career finally kicked into high gear. After landing the plumb second season role of a desperate gambler indebted to Tony Soprano on the hit HBO series "The Sopranos" in 2000, Patrick was tapped by producer Chris Carter to join the long-running "The X-Files" in the newly-created role of Agent John Doggett, the new partner of Gillian Anderson's Dana Scully. Patrick remained with the series until its swanson in 2002, and was also featured in several high profile motion pictures including "All the Pretty Horses" (2000), as Matt Damon's father, "Spy Kids," "Texas Rangers" (both 2001) and "Charlie's Angels 2: Full Throttle" (2003). His next major starring role was as a firefighter in the film "Ladder 49" (2003) opposite Joaquin Phoenix and John Travolta. Though still appearing in forgettable fare like the motorcycle film "Supercross" (2005, Patrick also proved continually potent when utilized in A material, like his turn as country music legend Johnny Cash's stern, unloving father Ray in James Mangold's superior biopic "Walk the Line" (2005).