Born in New York City, but raised in Chicago, IL, Piven was the son of Byrne and Joyce Piven, founders of the Piven Theatre Workshop, a company which would go on to nurture such future names as John and Joan Cusack, Rosanna Arquette and Aidan Quinn. Acting from childhood, he would later become a member of the Second City National Touring Company, a pivotal bit of comic training that would serve the young actor well later on in his career. Moving from the stage, Piven segued to features as one of the bullying jocks in "Lucas" (1986). His subsequent work included playing one of the Gas 'N Sip boys in Cameron Crowe's classic, "Say Anything" (1989), a film that starred Piven's childhood pal John Cusack; a sailor who gets duped by Cusack in Stephen Frears' "The Grifters" (1990); and one of the devoted fanatics in "Bob Roberts" (1992). With his career definitely on an upswing, Piven landed small roles in big films such as "White Palace" (1990), "Singles" (1992), "Miami Rhapsody" (1995) and "Heat" (1995). Just as importantly, Piven also began netting larger roles in smaller films, including "The Player" (1992), the romance "Twogether" (1992), the action flick "Judgment Night" (1993), and the troubled comedies "Car 54, Where Are You?" (1994) and "Dr. Jekyll and Ms. Hyde" (1995). His first starring role was as a trouble-making college student in the low-budget, boisterous "PCU" (1994), followed by another lead in the Oxford-set romance "E=mc2" (1995), and a turn as a writer romancing movie star Sherilyn Fenn in "Just Write" (1997). All good résumé-building experience, but nothing earth-shaking for his career.Making the right move at that time, Piven jumped to television, appearing as a stock player on Carol Burnett's short-lived variety series, "Carol & Company" (NBC, 1990-91), and making guest appearances on such shows as "Seinfeld" (NBC, 1990-98) and "Chicago Hope" (CBS, 1994-2000). But it was his 1992-93 stint on HBO's "The Larry Sanders Show" (HBO, 1992-98) which brought him his first real notice. As Jerry Capen, the over-the-top writer on the fictitious late-night talk show, Piven went all-out in hilariously portraying Capen's personal life meltdown, brought on by abuse of sex and drugs, until he was finally fired. He mastered that character to such an extent that he made a 180-degree turn back to normalcy with his role as an out-of-work dad on the short-lived sitcom "Pride and Joy" (NBC, 1995) and in the TV-movie thriller "12:01" (Fox, 1993). In 1995, he reclaimed a bit of his "Larry Sanders" bravado by appearing as Ellen DeGeneres' grating and obnoxious cousin, Spence Kovak (replacing the male lead vacated by Arye Gross), on the comedienne's successful sitcom, "Ellen" (ABC, 1994-98). After the show was cancelled, following the "outing" of DeGeneres' TV character, and a consequent massive ratings dive, Piven returned to series TV more than once in the late 1990s, starring in a pair of short lived, lighthearted ABC dramas, "Cupid" (1998), in which he played a man who believed himself to be the Greek god of love, and "Partners" (1999). Despite making a mark on both small and big screens, Piven still found time for stage work, co-founding with childhood friend Cusack the Chicago-based theater company, New Criminals. The experimental company allowed the actor to push the envelope, with him later going so far as to say, "unless an entire row of people got up in the middle of a performance and leave the theater in disgust, I feel as though I haven't done my job." Piven's real-life friendship with Cusack continued to prove fruitful, as he became the then bigger star's preferred sidekick/foil in several films, especially those which Cusack produced himself. The witty team demonstrated their considerable "buddy-buddy" chemistry in the ultra-quirky but endearing hit man-goes-home-for-high school-reunion comedy, "Gross Pointe Blank" (1997), in which Piven played hit man Cusack's teen crony-turned-dentist Paul. The two actors re-teamed in the romantic comedy "Serendipity" (2001), with Piven's best friend helping Cusack pursue the woman he may have been fated to fall in love with (Kate Beckinsale). The Chicago boys were both featured in the film adaptation of author John Grisham's legal potboiler "Runaway Jury" (2003), with Piven as a shrewd but inexperienced jury consultant.Even without Cusack, Piven began carving out a solid niche as a supporting player and character actor, usually playing a variation of his oily, comedic persona, but sometimes in straight dramatic roles as well, including in the feature films "Kiss the Girls" (1997), the HBO biopic "Don King: Only In America" (1998), "Very Bad Things" (1998), "The Family Man" (2000), "Rush Hour 2" (2001) and "Black Hawk Down" (2001). In 2003, Piven made the most of an underwritten role as the comic villain in the hit comedy "Old School," playing the dastardly, wound-too-tight college dean who attempts to thwart the fraternity created by middle-aged men Luke Wilson, Will Farrell and Vince Vaughn. Indeed, with his portrayal of Dean Gordon "Cheese" Pritchard, Piven seemed to pay tribute to such archetypal characters created in the late 1970s and early '80s by actors such as "Animal House" star John Vernon (Dean Wormer). That same year, he also landed a brief role as a bland newscaster in "Scary Movie 3," followed by the role of a Secret Service agent caught up in a romantic subplot in the vacuous Mandy Moore film, "Chasing Liberty" (2004). Thankfully for Piven, after playing second banana for so long, the actor scored his biggest role to date when the HBO series "Entourage" debuted in 2004. Although not a member of the four-man group of the show's title, he grabbed audiences and would not let go with his dead-on performance as the morally challenged, hard-driving, ultra-abusive talent agent Ari Gold. Piven was such a stand-out, he earned several Golden Globe and Emmy nominations. With his mother by his side, Piven finally received his well-deserved "Entourage" Emmy in 2006 for Best Supporting Actor in a Comedy Series.The following year, Piven received his second consecutive Emmy in the Best Supporting Actor category, this time going up against "Entourage" co-star Kevin Dillon, who was also nominated for his role as Vincent Chase's devoted brother and perennial hanger-on Johnny "Drama" Chase. Piven would repeat the win in 2008. In October 2008, Piven made a return to the stage for the first Broadway revival of David Mamet's "Speed-The-Plow," which also starred Elizabeth Moss and Raul Esparza. Piven was forced to leave the show, however, after he was diagnosed with extreme mercury toxicity. Priven reportedly felt dizzy and fatigued, and had difficulty lifting his arms or legs. Playwright David Mamet was initially skeptical of his sudden departure, saying "[M]y understanding is that he is leaving show business to pursue a career as a thermometer." Piven was allegedly disappointed with the lack of support, especially after having spent three days in the hospital. The actor had been an avid sushi eater for years, which has widely been seen as one of the causes of the illness. Meanwhile, after receiving yet another Golden Globe nomination for playing Gold, Piven and the rest of his "Entourage" castmates saw their show come to an end after eight seasons, though a 2015 movie brought the characters back briefly. Turning back to the big screen, Piven had supporting roles in "I Melt with You" (2011) and "Spy Kids: All the Time in the World" (2011) while voicing Black Bellamy in the animated adventure "The Pirates! In an Adventure with Scientists" (2012) and starring opposite Miley Cyrus in family comedy "So Undercover" (2012). Piven returned to television in the title role of "Mr. Selfridges" (ITV/PBS 2013-16), a British-made series about the founder of one of London's most beloved department stores. Between seasons, Piven ahd a small uncredited role in the Tom Cruise science fiction thriller "Edge of Tomorrow" (2014) and appeared in the noir sequel "Sin City: A Dame to Kill For" (2014). After the end of "Mr. Selfridges," Piven returned to network TV as the star of a crime procedural, "Wisdom of the Crowd" (CBS 2017). But after four different women came forward with allegations of sexual misconduct against Piven beginning in October 2017, the network shut down production of the series.