Haro

Haro is considered the mascot of the Mobile Suit Gundam series, appearing in the original Universal Century timeline, Gundam SEED's Cosmic Era timeline, Gundam 00's alternate take on the Anno Domini timeline, and Gundam AGE's Advanced Generation timeline. The robot companions spend most of their time in a ball-like form, but can sprout arms and legs whenever a situation calls for it.  They are capable of speaking, though they always repeat anything that they say a second time.
 
The original Haro is invented by Amuro Ray. It is very large (around basketball-sized), and follows Amuro's friend Fraw Bow throughout the series. They apparently become very popular in-universe, as Kamille Bidan, Hathaway Noa, Banagher Links, and Uso Ewin each own a Haro. Uso's Haro in particular is highly-intelligent and capable of operating mobile suits.
 
In Gundam SEED and SEED Destiny,  several Haros are built for Lacus Clyne by Athrun Zala. These Haros are much smaller, easily fitting in one's hands, and come in a multitude of colors.
 
Gundam 00's Haros serve as assistant droids for repairs and other operations. The two most notable Haros are Lockon Stratos's orange Haro, and Nena Trinity's rude purple Haro.
 
The Haro featured in Gundam AGE is created by Flit Asuno. This Haro has a "PC Mode" which allows it to be used as a normal computer. In the second generation, Haro is frequently seen with Asemu Asuno and Arisa Gunhale, while in the third generation it follows Kio Asuno and Wendy Hearts.
 

In Video Games

Harobots is a collect-em-all RPG in which the player character's Haro can imitate various Sunrise-created mecha.
 
In the Super Robot Wars series, Haro appears as an equipable item in almost every game that features a Universal Century Gundam series. (In games that feature Heavy Metal L-Gaim, Haro is replaced by L-Gaim's "Fatima") The Haro is arguably the best item in any game it appears in, granting several stat boosts beneficial to highly mobile units. The specific boosts vary by game, but generally include Mobility, Accuracy, Movement Range and/or Weapon Range. In Super Robot Wars 3, Haro is used to represent the pilot of an AI-driven machine. 
 
Several versions of Haro are included in the SD Gundam G Generation series as comedic, yet very powerful, units. SD Gundam G Generation World and Overworld allows players to recruit a Haro as a pilot. G Generation Portable and Spirits use a "Haro Point" system to determine the player's rank at the end of a mission; a Haro appears next to the player's score and changes color as the score passes certain thresholds.
 
In Kidou Gekidan Haro Ichiza: Haro no Puyo Puyo, different colored Haros replace Puyo as the blocks used in the game.