Gilgamesh OBD
Start praying, mongrels

Name: Gilgamesh, King of Heroes, Archer
Origin: Fate/Stay Night, Fate/Zero, Fate/Extra
Gender: Male
Classification: Servant/Heroic Spirit
Age: Unknown
Powers and Abilities: Super strengthspeeddurability, magic, enhanced senses, precognition, regeneration (mid-low), magic resistance (which extends to a wide range of magic effects like: mind manipulation, petrification and spatial manipulation), summoning (of his armor and weapons), telekinesis (via Gate of Babylon), space/time manipulation, flight and levitation, invisibility (Fate/Zero only), intangibility (Fate/Zero only), probability manipulation (grants supernatural luck to get rich quickly and never lose money to gambling), minor causality manipulation resistance, has the prototype form of every Noble Phantasm and anything that's considered to have been created by humanity stored in the Gate of Babylon | amplified stats, matter manipulation resistance, mind manipulation resistance, soul manipulation resistance, causality manipulation resistance, probability manipulation resistance, possibly time/space manipulation resistance
Weaknesses: He makes arrogant people look modest, doesn't actually know how to use a lot of the items in Gate of Babylon | Can only exist in the Mooncell 
Destructive Capacity: Island level+ with Gate of Babylon (is able to repel strikes from Berserker) small country level+ with Uncharged Ea (more than a match for Saber's full powered Excalibur and destroyed Rider‘s Ionioi Hetairoi); planet level with Full Powered Ea (as described by the narration of Fate/Strange Fake) | Likely much higher with Ea
Range: At least several hundred meters with GoB, several to dozens of kilometers with Enuma Elish, potentially planetary with a fully charged Ea
Speed: Massively hypersonic+ | Massively FTL+ (should be comparable to the rest of the playable servants with their mythic formal wear)
Durability: Island level+ (his armor has tanked numerous strikes from Saber, endures Shirou Emiya and Saber's Caliburn, and is comparable to Saber) | Large planet level+ (can live through Kiara Sessyoin's Noble Phantasm)
Lifting Strength: Class 25+
Striking Strength: At least Class EJ+ (comparable to Lancer and Saber) | At least Class EJ+, likely higher
Stamina: Tireless as long as he has a supply of mana; can sustain himself indefinitely without a master due to Independant Action (Zero and Extra Incarnation; although he would still require an outside supply of mana for extensive fighting)
Standard Equipment: Gate of Babylon, Ea, Enkidu, Vimana (not usable by his FSN incarnation as he had already lost it)
Intelligence: Fairly knowledgeable and intelligent. Can think out smart strategies for battle to ensure his victory, has surprising understanding of magecraft and can see through every magic that Shirou was preparing against him, although he’s extremely arrogant and apparently has a short fuse. However, it should be noted that he does not know how to use every noble phantasm in his vault. 
Notable Attacks/Techniques:

Enkidu - Chains of Heaven: The Noble Phantasm that Gilgamesh trusted the most, even more so than Ea. One of the few anti-god weapons that has the power to "reign over the gods". The higher the divinity, the stronger it is. At a sufficient amount of divinity, it binds space itself. Against those with no divinity, it's about as much trouble as a tough chain.

- Sword of Rupture, Ea: By compressing and accelerating wind pressure, it becomes a fake space-time dislocation that pulverizes any opposition. With an output power surpassing Saber's Excalibur, it is the "sword that cut the world apart". Strictly speaking, the Noble Phantasm is Ea, and Enuma Elish is the name of the attack at its highest power. It is the only Anti-World Noble Phantasm.

Gate of Babylon - King's Treasure: A small, plain sword that doubles as spatial key, allowing Gilgamesh to access his vast wealth contained within a vault in the heart of ancient Babylon. Inside this treasury are a myriad of Noble Phantasms collected during the peak of Uruk. Gilgamesh either throws these weapons or fires them out of his vault like rockets; it is this Noble Phantasm that designates Gilgamesh as an Archer-class Servant. Any weapons or artifacts discharged by Gate of Babylon return to the vault after an indeterminate amount of time. Because he lacks proficiency with any of these weapons, Gilgamesh will typically only fire the weapons as projectiles; in several instances, Gilgamesh has removed and normally wielded weapons. By word of god, all weapons that any heroic spirit has is retroactively added to his vault, even if he shouldn't have them.

Golden Rule: Throughout history and mythology, individuals destined to amass vast fortunes and treasure are identified as possessing Golden Rule. Among these figures, Gilgamesh stands alone at the zenith of opulence, for he has at his disposal enough riches to purchase whatever he may need in any era of summoning.

Notable OBD Victories:

Ares (God of War) - Ares Profile
Dante (Devil May Cry) - Dante Profile
Meruem (Hunter x Hunter) - Meruem Profile
Rhode Kamelot (D.Gray-Man) - Rhode Kamelot Profile
Sakura Matou (Fate/Stay Night) - Dark Sakura Profile
Scourge (Warcraft)
Soul Society (Bleach)
Tasha Godspell (Witch Hunter) - Tasha Godspell Profile
Ulquiorra Schiffer (Bleach) - Ulquiorra Profile

Notable OBD Losses:

Cloud Strife (Final Fantasy) - Cloud Strife Profile
Former Crimson King (Samurai Deeper Kyo) - FCK Profile
Jack Rakan (Negima) - Jack Rakan Profile
Laharl (Disgaea) - Laharl Profile
Sol Badguy (Guilty Gear) - Sol Profile
Yusuke Urameshi (Yu Yu Hakusho) - Yusuke Urameshi Profile
Xellos (Slayers) - Xellos Profile

Contested OBD Matches:

Accelerator (Toaru Majutsu no Index ) - Accelerator Profile

Other:

Key: Servant Gilgamesh | Fate/Extra CCC with Mythic Formal Wear (Mooncell only)/Gilgamesh when he was alive

Every weapon in the Gate of Babylon has some enchantment or effect. Also, he likely can't use Gae Bolg: Piercing Death Thorn