There are many great TV series featuring detectives as the main character. Here are a few popular options:
1. True Detective: This HBO series follows the journey of two detectives as they investigate a murder and uncover a vast conspiracy. Season 1 is widely considered to be one the best seasons of TV of all time.
2. The Wire: This HBO series follows the lives of criminals, cops, and civilians in Baltimore. It's a smart, thought-provoking show that offers a nuanced view of the criminal justice system.
3. The Night Of: This HBO miniseries follows the journey of a young man who is falsely accused of murder. It's a tense, nail-biting story that will keep you on the edge of your seat.
4. Mindhunter: This Netflix series follows the journey of two FBI agents as they interview serial killers in the 1970s. It's a disturbing but addicting show that explores the psychology of evil.
5. Columbo: This classic murder mystery show follows a detective named Columbo as he solves crimes. It's a fun, lighthearted show that is a joy to watch.