Rajeshkumar Novels have been the primary draw for Tamil thriller enthusiasts and Tamil thriller movies have been influenced by Rajeshkumar Novels. 
It has various subgenres, here's the list of top ten best Tamil thriller movies.
 

1. RATCHASAN:(2018)
  It is considered a best among the top Tamil Thriller movie and received many positive reviews. The movie was a huge success at box office.
It has unique storytelling, well crafted suspense and tension. The BGM is the backbone of the movie. The music still haunts even after so many years of the movie's release. 
The hero's strong performances and thought provoking themes are the reason why the movie stands out. 
The antagonist in the Ratchasan is a Masterclass in the suspenseful storytelling making the film a gripping thriller. 
Ratchasan's expertly designed thriller elements ensure a heart-stopping, pulse pounding experience. There are many nail biting moments in the movie where the audience were scene seated at the edge of the seat. 
Ratchasan has become the benchmark for Tamil Thrillers, influencing the genre.

2. DEMONTE COLONY: (2015) 

This stars Arulnithi as the hero. 
Directed by R. Ajay Gnanamuthu Demonte Colony achieved remarkable box office success. 
This movie tells the chilling tale of four friends who spend a night in the infamous Demonte Colony, a haunted location in Chennai. After the night in Demonte Colony, the friends unwittingly carried home an evil presence, sealing their fate.
 With a strong cast, including Arulnithi, Ramesh Thilak, and Sananth Reddy, Demonte Colony delivers convincing performances that amplify the terror. The movie's success can be attributed to its unique narrative clever plot twists, and Gnanamuthu's skillful direction, which effectively exploit the fear of the unknown. Demonte Colony received widespread critical acclaim, cementing its place as one of Tamil cinema's most frightening and memorable horror films.
Unlike other movies, Demonte Colony boasts a refreshingly original narrative. 
It was highly anticipated to have a sequel, sparking excitement among fans. Nine years after the original, Demonte Colony 2 finally hit theatres in 2024.

3. PIZZA (2012) - directed by Karthik Subbaraj. The movie stars Vijay Sethupathi and Ramya Nambeesan in the lead roles. 
The movie revolves around Michael (Vijay Sethupathi) a pizza delivery boy and his pregnant wife Anu (Ramya). One day Michael goes to deliver pizza to a customer only to discover himself captive in a living hell tormented by eerie mysteries and a paralysing fright. 
As supernatural events unfold, the
customer's mysterious identity becomes central to the plot. Chilling revelations await as the customer's secrets unravel.
A haunting connection between the paranormal and mystery is exposed in the climactic finale of the movie. 
The title of the movie would make the audience from watery mouth to a sweaty body.
This movie is considered a turning point in Vijay Sethupathi's career establishing himself as a lead tamil actor in Tamil Cinema. Vijay Sethupathi became a sought after hero in Tamil Cinema thereafter.

4. THEERAN ADHIGARAM ONDRU(2017) is a movie directed by H.Vinoth. Karthi is the lead and Rakul Preet Singh is the heroine of the movie.  The film bagged many awards.
The movie is inspired by real life story of the infamous gang which terrorised Tamil Nadu in 1990s. 
Gibran's BGM enhances the film's tension and suspense. 
Karthi stars as Theeran, a determined
police officer tasked with cracking a series of heinous crimes plaguing Tamil Nadu. A notorious gang is wreaking havoc, leaving
a trail of gruesome murders and daring
robberies in its wake. With unwavering resolve, Theeran embarks on a perilous mission to unravel the mystery behind these shocking crimes.
H. Vinoth's film aims to deliver a gripping and realistic portrayal of the challenges faced by police officers in solving complex cases. By shedding light on the unrelenting world of crime investigation, Vinoth seeks
to expose the intricacies and obstacles that law enforcement officials encounter. 
Theeran adhigaram ondru recieved widespread critical acclaim as the best movie. Must watch movie.

5. POR THOZHIL (2023) is an investigative thriller starring Sarathkumar and Ashok Selvan in the lead roles. This movie is about a brilliant but apprehensive rookie cop lands his first case, he's forced to face his fears head-on, teaming up with a grizzled, solitary senior detective to hunt down a cunning serial killer wreaking havoc on the community".
This gripping crime thriller holds you captive until the very end.
This movie leaves the message to all the parents about the importance of nurturing and loving the children and giving them the good childhood memories with love and care.
Overall a good thriller with all elements placed correctly with a good BGM as Cherry on top.

6. VIKRAM VEDHA (2017) features R.Madhavan as Vikram, the Police officer and Vijay Sethupathi as Vedha the notorious gangster. The movie is about Cop v/s gangster or a cat and mouse story. Vikram, a seasoned and practical police officer, and his trusted partner Simon are relentlessly pursuing the elusive gangster Vedha. However, in a shocking turn of events, Vedha surrenders himself to Vikram, but only on the condition that he listens to a captivating story.
As Vedha begins to narrate his tale, Vikram's world is turned upside down, forcing him to confront his own moral ambiguities and question everything he thought he knew about justice, morality, and the true nature of evil.
Madhavan and Vijay Sethupathi deliver powerhouse performances as Vikram and Vedha respectively. This movie has a famous dialogue "Oru Kadha Solta Sir ".  
The climax received many critical acclaim  as the best climax.
Must watch movie.

7. DIARY (2022)

 The film stars Arulnithi as the lead. Diary tells the story of a sub inspector trainee, who sets out on a journey to track an unsolved 16 year old case as his assignment, unaware that his journey will become a thrilling ride of twists and turns, driven by destiny.
The movie begins as an investigative piece, and skillfully navigates the complexity of human emotion and supernatural presence, ultimately delivering a mesmerising and emotional resonant conclusion. This is a captivating fusion of genres.
"Diary, directed by Innisai Pandiyan, revolves around the stories and lives of desperate individuals, forging a poignant narrative of chance encounters and life-altering consequences. 
Inspired by the infamous, unsolved mystery of China's Bus Route 375, this gripping film masterfully adapts a real-life incident into a thrilling narrative. The director skillfully expands on a tantalizing concept, crafting an intricate web of suspense that keeps viewers on the edge of their seats. 
The film's climax masterfully converges emotion and clarity, addressing all lingering questions and leaving the audience with a profound sense of satisfaction.

8. DEJAVU (2022)

 When the state DGP's daughter vanishes echoing the plot of a crime novelist's latest story, an undercover officer must navigate the blurred lines between fiction and reality unravel the truth. 
The plot of the movie concerns an author Subramani, stumbles into a police station, intoxicated, claiming he has been receiving death threats by phone because of a book he has written showing the perpetration of a crime. He believes the killer in the book is the one making him the phone calls. The police take him lightly, but his complaint is lodged. Soon a phone call arrives by a woman that claims the writer Subramani was involved in her kidnapping.
"Dejavu" is a gripping thriller that
masterfully weaves together elements
of suspense, mystery, and intrigue.As the story unfolds, the lines between reality and fiction blur, leading to a stunning climax that will leave audiences breathless. It is a must watch movie.

9. VETTAIYADU VILAYADU (2006) This movie stars Kamal Hassan and Jyothika directed by Gautam Vasudev Menon. This movie cemented GVM's status as a prominent director in tamil Cinema.
This movie is about a police officer who tackles a gruesomen cross-border crime spree involving serial rapes and murders. 
Kamal Haasan's phenomenal acting talent takes center stage, captivating audiences with a riveting performance that's both nuanced and powerful.
Balaji delivers a haunting performance as Amudhan, capturing the complexity of the cold-blooded killer.
Harris Jayaraj's music is notable. Songs are hummable and foot tapping.
The movie has a famous dialogue "En Kannu venumnu Ketiyamey?". 
All in all a racy thriller with all the ingredients to watch it over n over.

10. D BLOCK (2022) by Vijay Kumar Rajendran. 
Arulnidhi steps into the spotlight as Kumar, the young student in the movie who moves into the new hostel block named D Block to pursue his higher studies. 
However his academic journey takes a dark turn when he encounters many unsettling supernatural events that hint at the block's haunted past. Mysterious disappearances of the female hostel students have sparked alarm and concern.
Kumar, teams up with his friends and a professor to unravel the mysterious forces behind the paranormal activities. 
As they delve deeper, they confront many terrifying secrets and sinister forces head on, racing against time to expose the dark reality behind D block's Haunting.
The past story which unfolds was too scary. Ending was so justified and well made.

In conclusion, thriller movies captivate audiences with their successful plots,complex characters and shocking twists and emotional resonance, leaving a lasting impact on the popular culture.