Paul Rudd
The affable actor had a recurring part as Bobby Newport, who was both the future heir to the sugary Sweetums company, as well as Leslie's Pawnee City Council opponent who could care less if he wins the job.
Keegan-Michael Key
The Key & Peele actor recurred as Joe, who went from being introduced as Donna's ex-boyfriend to her husband by the end of the series.
Andy Samberg
The Saturday Night Live alum had a memorable, hilarious part as Carl Lorthner, the literally loud-mouthed Parks Security employee.
Sean Hayes
The Will & Grace alum made a brief appearance on the show as Buddy Wood, a big-time reporter from Indianapolis who interviews Leslie as she runs for city council and insults Pawnee in the process.
Dax Shepard
Dax Shepard showed up in the show's final season as Hank, the boss at the TV studio that aired Andy's program "Johny Karate."
Jonathan Banks
Jonathan Banks played Ben Wyatt's dad, Steve, on the show, a far cry from his terrifying role as a hit-man on Breaking Bad.
Chelsea Peretti
Before starring in Brooklyn Nine-Nine, Chelsea Peretti had a small role on-screen as Zelda, a woman at a city council meeting, but had a larger role behind-the-scenes of the show as one of its staff writers.
Questlove
The Roots drummer Questlove made a fun appearance in the series as Levondrius, Donna's estranged brother.
Cory Booker
The U.S. Senator, who is dating actress Rosario Dawson, makes a cameo on the sitcom.
Bradley Whitford
The West Wing alum plays Councilman Larry Pillner, whose seat Leslie fills after she runs for city council.
Bo Burnham
The comedian played Chipp McCapp, a country musician whose music video "Beautiful Like My Mom (Support the Troops)" was hilarious, and kind of a bop.
Jon Hamm
We saw Jon Hamm's comedy chops when he showed up as Ed, a National Parks Service employee who Leslie calls "the most incompetent person" she's ever met.
Justin Theroux
The Leftover's Justin Theroux played Justin Anderson, one of Leslie's boyfriends before she found her happily-ever-after with Ben Wyatt.
Joe Biden
The now-Democratic Presidential nominee was a favorite of Leslie Knope's back when he played himself in Barack Obama's administration.
Michelle Obama
Leslie Knope could barely even speak when she met up with one of the best First Ladies of all time, Michelle Obama.
Kristen Bell
The Good Place's Kristen Bell appeared on this NBC sitcom as well when she played Ingrid de Forest, a stuck-up councilwoman from Pawnee's rival city, Eagleton.