Bronze:

High Roller
Objective: Win over 2000 chips in a hand of Poker.

No Dice
Objective: Complete a game of Liar's Dice without losing a single die.

What About Hand Grenades?
Objective: Get a ringer in a game of Horseshoes.

Fightin' Around the World
Objective: Knock someone out in melee in every saloon in the game in Single Player.

Strange Things are Afoot
Objective: Complete a task for Stranger.

Buckin' Awesome
Objective: Break the Kentucky Saddler, the American Standardbred, and the Hungarian Half-bred.

Clemency Pays
Objective: Capture a bounty alive.

Exquisite Taste
Objective: Purchase a rare weapon from a gunsmith.

Bearly Legal
Objective: Kill and skin 18 grizzly bears.

He Cleans Up Well!
Objective: Obtain the Elegant Suit.

More than a Fistful
Objective: Earn $10,000 in Single Player.

Frontiersman
Objective: Obtain Legendary rank in any Single Player Ambient Challenge.

Man of Honor / Chivalry's Dead
Objective: Attain highest Fame rank and either highest Honor rank or lowest Honor rank.

Gold Medal
Objective: Earn a Gold Medal Rank for a combat mission in Single Player.

On the Trail of de Vaca
Objective: Uncover every location on the map in Single Player.

Friends in High Places
Objective: Use a pardon letter with more than $5000 bounty in Single Player.

Bullseye
Objective: Get 250 headshots in any game mode.

Unnatural Selection
Objective: Kill one of every animal species in the game in any game mode.

Slow on the Draw
Objective: Get 10 assists in a single Hideout in a public Free Roam session.

Hit the Trail
Objective: Get from Blackwater to Escalera before sundown in a public Free Roam session.

Posse Up!
Objective: Create a posse and get the maximum number of members.

Most Wanted
Objective: Become a Public Enemy for 10 minutes and escape alive in a public Free Roam session.

Red Dead Rockstar
Objective: Kill a Rockstar or someone with this Trophy in a public multiplayer match

Austin Overpowered
Objective: Complete Twin Rocks, Pike's Basin, and Gaptooth Breach Hideouts in Single Player.

Silver:

Evil Spirits
Objective: Complete Tumbleweed and Tesoro Azul Hideouts in Single Player.

Instinto Asesino
Objective: Complete Fort Mercer and Nosalida Hideouts in Single Player.

People are Still Strange
Objective: Complete 15 tasks for Strangers.

The Gunslinger
Objective: Score a headshot on any enemy using Expert targeting mode.

Mowing Them...