Christopher Cesar Portugal (born October 18, 1977), best known as Thes One, is an American rapper, record producer and sound engineer. As one half of hip hop duo People Under the Stairs alongside Double K, serving as a vocalist/MC, producer and business manager, he produced and engineered 12 albums for People Under the Stairs that appeared on the U.S. and International Billboard charts numerous times, as well as remixes and singles for various artists across the globe and appearances as guest vocalist. As a business manager, he coordinated world tours for People Under the Stairs, co-founded the independent artist-run Tres Records label and went on to create Piecelock 70, a self run, independent record label and brand in 2004. People Under the Stairs announced their intention to retire in early 2019 following the release of their 12th and final album Sincerely, The P, and his career and contribution was celebrated by the Los Angeles Times in a full page article.

Additionally, he designs and builds recording studios and custom gear, guest lectures at colleges and graduate programs about AI, financial literacy and music history and continues to create music following the death of his partner. His musical aliases include Lord Radio.

Born Christopher Cesar Portugal in Torrance, California to an American mother and immigrant Peruvian father, Thes One grew up in San Pedro, California. He was first introduced to hip hop at Peck Park childcare, where older counselors would paint graffiti in the empty public pool and play the now defunct AM radio station 1580 KDAY. While attending high school in Los Angeles, Thes One met Michael Turner (Double K), and the two began working together as what would soon become People Under The Stairs.

Upon graduating from Loyola High School in 1995, he applied to Berklee School of Music in Boston for a BA in Audio Engineering but received a writing scholarship to USC, where he was chosen for the prestigious honors English program. While there, he studied under his advisor Percival Everett, received the Seibert Fellowship for poetry, acceptance to the Golden Key Honors Society and walked in 1998 Magna Cum Laude with Dean's Honors.

While studying at USC, he began recording music with Michael Turner as People Under the Stairs, and in 1997 they performed their first in-store appearance as a group at the now defunct Beat Non Stop record store on Melrose. That year they also took a trip to the Bay Area, and upon returning, wrote and recorded "San Francisco Knights", one of the group's most popular songs.

In the spring of 1998, months before graduating and using his student loan funding, Thes One independently released the first People Under the Stairs 12-inch entitled The Next Step Pt. 2. 250 of the original vinyl run were made until the stamper broke, at which time an additional 200 were made from a different master without the secret bonus track "Live at the Fishbucket", which appears on the first run B-side. In late summer 1998, he independently released their first album entitled The Next Step, which he also produced and engineered in its entirety.

After selling out of the vinyl 12-inch in 7 minutes, the shopkeeper at Mr. Bongo's record store in London called Chris Smith, label owner of Om Records, and urged him to get in contact with the group. Chris Smith contacted Thes One initially for one song for their compilation series Deep Concentration and Mushroom Jazz, but upon hearing the tracks they were working on, offered P.U.T.S. a four-album deal.

The deal was signed in 1999 and P.U.T.S. left for their first world tour in August 1999, initially as support for the Deep Concentration project but later that year in Europe as a Solo Act with local openers.