TX-55 METAL GEAR
TX-55 is the mech featured in the first Metal Gear game from 1987. It was made in Outer Heaven in 1995 and was destroyed by the then-rookie Solid Snake during Operation Intrude N313. It's existence, and the threat of it launching a nuclear missile, made other countries afraid to attack Outer Heaven. It was developed by Dr. Madnar, who was kidnapped by Outer Heaven soldiers and forced to build the deadly weapon.
Aesthetics-wise, TX-55 is more rounded and bulky-looking than the robots featured in later MGS titles. Personally it reminds me of Makoto Kobayashi, an artist who's worked on several mecha anime, for example Dragon's Heaven in 1988. His mechs all have a grainy, almost organic sort of style which gives them a very unique look. Though it might differ from what's popular in mech design during the 21st century, I really like the look of the TX-55 and it's succesor, Metal Gear D from Metal Gear 2: Solid Snake.
Though it was supposed to be Outer Heavens "ultimate weapon" of sorts, in retrospect it seems almost unimpressive compared to some of the more advanced metal gears that existed chronologically earlier in the series such as the AI weapons from Peace Walker. But obviously the development team had no idea what the future would hold. O_o *looks over at MGS2* Okay on second thought, maybe there were some fortune tellers among the writers...