Diamond Dogs

The Diamond Dogs are three supporting antagonists who appear in the episode A Dog and Pony Show. After they see Rarity using her gem-finding spell, they kidnap her and force her to find gems for them. They aren't particularly smart and Rarity tricks them easily.

Development
Lauren Faust stated that the names the Diamond Dog leaders were given in the script are Fido, Rover, and Spot. However, she didn't recall which ones have which name. Jayson Thiessen, the show's supervising director, later confirmed their names.  Rover, the medium-sized dog, is the leader of the trio, while Fido is the large-sized one and Spot is the small, bulldog-like one. Rover is voiced by Scott McNeil, Fido is voiced by Garry Chalk and Spot is voiced by Lee Tockar. The name, Diamond Dogs, is a reference to David Bowie's 1974 album of the same name.

Depiction in the series
The Diamond Dogs secretly watch Rarity and Spike as they collect gems, initially thinking Spike is the gem finder, before realizing that Rarity is using her magic to find them. They then make themselves known and tell Rarity they hunt for gems, and will hunt for her since she can find the gems. They have a tussle with Rarity and Spike but manage to abduct Rarity into their extensive system of underground mines. A Diamond Dog guard riding Applejack.They attempt to force Rarity to find gems for them, but Rarity puts on a complaining and whining act, tricking them into doing all the work while she relaxes. When Rover gets wise to this, he forces Rarity to pull the gem cart, calling her a mule. In response, Rarity acts hurt, crying loudly about being compared to an "old, ugly mule." By the time Rarity's friends arrive to save her, the Diamond Dogs are begging for Rarity to leave, even letting her take all their gems with her.

The three main Diamond Dogs wear jackets and diamond-studded collars, while the rest of the Diamond Dogs wear metal armor and carry lances. They alternate between walking on their hind legs and all fours, their elongated forelegs giving them a gorilla-like appearance. They also have short and stubby spiked tails.

Their voices and some of their mannerisms appear to be based off and inspired by the Lord of the Rings character Gollum.

Role in the SAF Series.
In the Lore of Equestia in the Spongebob and Friends series, Diamond Dogs were once allies to the ponies during the Unity days.... when it comes to jewel trade. It wasn't a sour relationship but it was also strictly business. Everything was find until the "Pony Slavery Foundation" in the olden times, run by Trolls, Hobgoblins, Dragons, and Founded by The griffins, began to draft other non-pony creatures into turning ponies into mule labor like farming and horse based means. The Diamond Dogs ended up becoming greatly corrupted by this "Idea" since some ponies can magicly find jewels in a snap. the Diamond Dogs of back then joined the foundation and propsered in Pony Labor. However, Celestia finally desided to put her hoof down and banned slavery. Almost all races, even the ones respondsable for the foundation that disbanned, bowed to this except the Diamond Dogs due to the Alpha King being greatly corrupted by greed. Cause of this, the king was captured and punished via magic stoneication, and the Equestian Council forced Celestia to banished Diamond Dogs from the Unity, forever cementing the dogs in an eternal age of greed that redused them to basicly be bandits and aductors. The Modern Dogs continued these traditions, and now, the pack run by Fido, Rover, and Spot, are about to become goons of Team Nefarious. And later down the road, other Diamond Dogs in the Spongebob and Friends series will persist to be a problem in more ways then one.