Kumail Ali Nanjiani (born May 2, 1978) is a Pakistani-American stand-up comedian and actor. He is known for his role as Dinesh in the HBO comedy series Silicon Valley (2014–2019) and for co-writing and starring in the romantic comedy film The Big Sick (2017). For co-writing the latter, he and his wife Emily V. Gordon were nominated for the Academy Award for Best Original Screenplay. In 2018, Time magazine named him one of the 100 most influential people in the world. He was nominated for the Primetime Emmy Award for Outstanding Guest Actor in a Drama Series for his role in The Twilight Zone executive produced by Jordan Peele in 2019.

Nanjiani has also voiced Prismo on the animated series Adventure Time and starred in the TNT series Franklin & Bash and the Adult Swim series Newsreaders. He also co-hosted the Comedy Central show The Meltdown with Jonah and Kumail, as well as playing various roles on the comedy series Portlandia. He also played Kingo in the Marvel Cinematic Universe (MCU) superhero film Eternals and What If...? Episode What If... Agatha Went to Hollywood?, con artist Haja Estree in the Disney+ miniseries Obi-Wan Kenobi and celebrity scientist Vik in the television series The Boys Presents: Diabolical and The Boys. In 2022, he starred in the lead role of the Hulu miniseries Welcome to Chippendales. In 2023, he was nominated for a Primetime Emmy Award in the Outstanding Lead Actor in a Limited or Anthology Series or Movie category for his work in Welcome to Chippendales. In 2025, he had a guest role in the second season of the crime mystery series Poker Face.

Nanjiani grew up in Karachi, the first of two sons of a Sindhi Shia Muslim couple Shabana and Aijaz Nanjiani. The BBC radio presenter Shereen Nanjiani is his second cousin. During his childhood, he lived in Karachi and attended St. Michael's Convent School for his O-Levels and graduated from Karachi Grammar School to complete his A-Levels, where he was the class-fellow of Sharmeen Obaid Chinoy. At 18, he moved to the U.S. and enrolled at Grinnell College in Grinnell, Iowa, where he graduated in 2001 with a double major in computer science and philosophy. He then moved to Chicago and began performing stand-up comedy at open-mic events.

In 2007, Nanjiani wrote and staged an original autobiographical one-man show in Chicago, New York, and Los Angeles. After moving to New York, he continued to perform stand-up and made occasional appearances on shows including Michael & Michael Have Issues and The Colbert Report. In 2009, he performed at the Just for Laughs comedy festival. In 2011, Nanjiani and X-Play staffer Ali Baker began hosting a video game-themed podcast, titled The Indoor Kids. In late August the same year, Baker left the show and Nanjiani began hosting with his wife, Emily V. Gordon. Until other commitments took over, he appeared regularly on Dan Harmon's podcast Harmontown, where he played Dungeons & Dragons with Harmon as a character named Chris de Burgh. He played a delivery man in the 2013 film The Kings of Summer. In addition to guest-starring in comedy shows like Portlandia, Nanjiani was featured in a supporting role in the TNT series Franklin & Bash. He played the role of Pindar Singh, an agoraphobic fiction nerd working for the title characters.

Nanjiani guest-starred on HBO's Veep as a statistician. He had the recurring roles of Amir Larussa on Newsreaders and Prismo on Adventure Time. His Comedy Central special Beta Male aired in July 2013. In late June 2013, Comedy Central announced the pickup of The Meltdown with Jonah and Kumail, hosted by Jonah Ray and Nanjiani. The show, featuring Nerd Melt comedy regulars and various comedians, began airing in July 2014. In April 2014, he began playing the character Dinesh in the HBO sitcom Silicon Valley. He voiced Reggie in the video game The Walking Dead: Season Two. In July 2014, Nanjiani hosted a weekly podcast titled The X-Files Files, dedicated to discussion and reminiscences about The X-Files. Each episode features Nanjiani and a guest, including former The X-Files writers, producers, actors and directors, in light-hearted banter about one or two episodes of the series. On July 30, 2014, Nanjiani appeared on Ken Reid's TV Guidance Counselor Podcast.

In 2015, Nanjiani guest-starred in the Broad City episode "In Heat". Starting on March 22, 2015, he provided his voice for the character of Mshak Moradi in the Hunt the Truth audio drama, part of the marketing campaign for Halo 5: Guardians. On May 5, 2015, he appeared on the Inside Amy Schumer episode "12 Angry Men Inside Amy Schumer", a parody of 12 Angry Men, as one of the jurors. In July 2015, Nanjiani provided guest voices on Aqua Teen Hunger Force and Penn Zero: Part-Time Hero.

In 2017, Nanjiani starred in the romantic comedy film The Big Sick, which he wrote with Gordon. The film is about their relationship, with Nanjiani playing himself and Zoe Kazan playing Gordon (renamed Emily Gardner). The film was one of the most acclaimed of 2017, and was chosen by American Film Institute as one of the top 10 films of the year and nominated for the Academy Award for Best Original Screenplay. The film was also the third-highest-grossing independent film released in 2017, grossing over $40 million.

In 2018, he was invited to the actors and writers branch of the Academy of Motion Picture Arts and Sciences.