Why does Darth Sidious need bodyguards?

Question

Darth Sidious had red-robed bodyguards on his shuttle and in his throne room.

Why would a Sith Lord need bodyguards?

He is an evil space wizard who can read minds, choke the life out of somebody just by talking to them during a video chat, and levitate multiple enemies during combat. People with those kinds of powers don't need guards. I could see Chancellor Palpatine having guards around him while he is out in public, but he would not need any in private. When Darth Vader brings Luke Skywalker to the throne room on the Death Star, the Emperor orders his guards to leave. It's not as if the guards could have intervened anyway.

Answer 1

This is addressed in a slightly tongue-in-cheek footnote in the new (canon) junior novelisation for Return of the Jedi. In short, the guards are basically window-dressing, for the most part, but the Emperor does like having them around to run errands and because they inspire awe in his visitors.

“Guards, leave us,” calls the Emperor, and his silent, red protectors glide away.¹

¹ The Emperor doesn’t really feel the need to be guarded. He only keeps these guards around to impress visitors. Now that they’ve been seen, they are free to take the service elevator down to their break room and take off their ridiculous helmets until called upon again.

_{^{Return of the Jedi: Beware the Power of the Dark Side!}}

Answer 2

Sidious was well aware of how he killed his own master, Plagueis: in his sleep. Sidious needed to sleep, too, and during that time he was relatively vulnerable. Sidious intended to live forever so he could not give Vader (or anyone else) any opportunity to kill him. Hence, the Royal Guard acted as an insurance policy to help make sure Sidious could not be killed even when he was relatively vulnerable.

Also, the Royal Guards carried a large variety of weapons which were unseen underneath their capes:

Two members of the Royal Guard, covered head-to-toe in the blood-red armor indicative of their order, flanked the door. Each held a stun pole at station. Vader knew that each of their crimson capes hid a heavy blaster pistol, a vibroblade, and various other weaponry.

_{Lords of the Sith, p. 27}

Some of these weapons have capabilities that Sidious did not have. In particular, a blaster pistol would probably have a longer range than even Sidious' Force Lightning.

Furthermore, the Royal Guards did prove themselves to be useful as bodyguards during the events of the novel Lords of the Sith, in which Sidious and Vader were attacked by Twi'lek rebels and a nest of lyleks on the planet Ryloth. When the attack began Sidious and Vader were theoretically quite safe on the Star Destroyer Perilous, but an attack forced them (and several Royal Guards) to evacuate the destroyer and crash-land on Ryloth. The danger was significant enough that the captain of the Royal Guard was killed defending the Sith Lords in combat.

It's also worth noting that Sidious' power as Emperor was justified in public in large part by the Jedi attack on him at the end of the Clone Wars. Sidious, known publicly as Palpatine, maintained a public persona as a kindly old man who was brutally attacked by the Jedi and was forced to (reluctantly) transform the Republic into the Empire and wield supreme power as the Emperor. Due to this attack, it was necessary for Palpatine to appear in public only with bodyguards (lest some rogue Jedi attack the poor, defenseless old man again!).

Not only were the Royal Guard necessary to maintain the fiction that Sidious was a defenseless old man who legitimately feared a Jedi assassination attempt, but the Royal Guard were among the very few who could be trusted to keep Sidious' secret:

[Vader] seldom saw his Master so publicly demonstrate his power. And he understood what it meant, of course. There must be no survivors who could bear witness. Only the Royal Guards could be allowed to live — only they could be trusted never to reveal what they’d seen, or even to talk about it among themselves.

_{Lords of the Sith, p. 168}

and obey Sidious without question:

"Kill him," [Sidious] said. The leader of the Royal Guard, conditioned to obey any order of the Emperor instantly without question, did not hesitate. He stood, drew his heavy blaster, and shot his comrade once in the head, leaving a dark, smoking hole in his helmet.

_{Lords of the Sith, p. 148}

As trusted lackeys the Royal Guards could be used to help keep Sidious' secret...and since the Royal Guard also obeyed Sidious without question, they could be ordered to execute anyone (even a fellow Imperial) who was not trusted enough to know Sidious' secret.

It's true that Sidious usually has little need of the Royal Guard when in private (especially on the Death Star), but why not use them in private as well as in public if he's gone through the trouble of conditioning them to obey him without question and reveal his secret to no one?

Answer 3

There are many historical monarchs that can fight very good when they're in battle, yet they still need guards, like Julius Caesar - who's one of Palpatine's historical inspirations IIRC - for example: https://en.wikipedia.org/wiki/Praetorian_Guard

In the year 27 BC, after Rome's transition from republic to empire, the first Emperor of Rome, Caesar Augustus, designated the Praetorians as his personal security escort.

The point of the guards is to convey his status as the Emperor, I mean look at how they stand around to make way for him on Death Star II:

And to maintain the illustion that he's a weak old man who was scarred by the Jedi:

Answer 4

The Emperor's guards help maintain the illusion that Palpatine is a feeble, old man. It's actually a very good ruse to help him maintain control over millions of planets.