- "Thanatos Squad? Those guys give me the creeps."
- ―A clone trooper, voicing his opinion about Thanatos Squad
- "That's a lot of clankers... ready to go have some fun, boys?"
RC-3333, more commonly known as "Reaper", was the leader of Thanatos Squad. Reaper held the rank of captain, and was as loyal to his squad as they were to him. Despite his infamous reputation as being quiet and quite sadistic, much of what came out of his mouth was jokes, or other comedy-related things, although he often did keep to the sadistic reputation when joking. Like most other clones, Reaper saw his squadmates as brothers, and often treated them like such.
- "Hey guys, watch this. I can juggle three Geonosian heads at once!"
RC-3327, more commonly known as "Doom", was a member of Thanatos Squad, and the others often viewed him as the second-in-command, although there wasn't an official second. Doom's jokes were the most sadistic of the group, and were often seen as the most funny by the others. Doom was the demolition specialist of the group, and preferred anything the exploded.
- "Check out this knife I found on a dead Geonosian. It has two blades for double the death."
RC-3307, more commonly known as "Scythe", was a member of Thanatos Squad. Scythe jokes the second least, but is also the most sadistic. Scythe was known as the weapon specialist of the group, and often used long-ranged weaponry and blades. Although he didn't joke a lot, he still enjoyed hanging around with his brothers as much as they did.
- "Stay focused, we have a job to do. And cut the chatter, I can't even hear myself think!"
RC-3339, more commonly known as "Grim", was a member of Thanatos Squad. Grim was the most serious of the group, and was known to discourage the others from joking on missions were concentration was important, although on less important missions he let them have their fun. Although he was the most serious, he would still joke around when off-mission, although he still did it the least. Grim was also known to be the team's technical specialist, and often did slicing and code-breaking. He was perhaps one of the most loyal of the group, second only to Reaper.
- Grim: "Hmmm... This door has some really complicated coding."
- Reaper: "Can you crack it?"
- Grim: "In my sleep."
- ―Grim and Reaper, about Grim's technological skills
Like all squads of republic commandos, Thanatos Squad wore Katarn-class armor, which was far stronger and more durable than the armor worn by regular clone troopers. Thanatos' armor was black, with dark red markings that were in no particular pattern. Other troopers often thought the pattern-less markings were supposed to look like blood, and some even speculated that it might be actual blood. Like the others commando squads, Thanatos was given DC-15s blaster pistol sidearms and DC-17m Interchangeable Weapons System. Each member was known to use a different attachment of the DC-17m, choosing it to their personal preference. They all also retrieved weapons from their different missions, and were known to have an expansive arsenal by Order 66.