Old men are weak, right?
When it comes to fiction, more often than not the oldest, apparently feeblest characters are the ones to be feared the most. They kick ass, take names, and can fend off armies single-handedly. If he's part of a Badass Family that has a Papa Wolf, this would be his Papa Wolf.
Old men in a dangerous line of work have been doing it for a very long time, and only lived that long because they've been smarter and/or stronger than everyone they've faced. Additionally, in a Crapsack World, or when Earth Is a Battlefield, a man may well only live to be old if he is already very bad-ass to start with.
Your badass old guy is likely to be tougher and cooler than just about everyone else, but given the subjective definition of the term Badass, it's just hard to define a trope that in theory could be any number of badass qualities matched with equally subjective old age where both aspects are relevant.
However, we have singled a few out. Please direct appropriate wicks to the following tropes:
- Cool Old Guy — Someone who is exactly as spry and tough and awesome as when they were 20, even 60 years later
- Eccentric Mentor — His eccentricities are often a combined sign of age and incomprehensible skill, so listen wisely, young one
- Never Mess with Granny — His Distaff Counterpart. When an elderly character, often a grandma to further the innocent and harmless imagery, is revealed to be packing ninjutsu and a bazooka
- Old Master — They have spent so many years mastering their art form that nobody can beat them
- Old Retainer — A member of a team who has been around so long that they are an inherent part of what makes the team
- Old Soldier — An older member of the armed forces who is still effective and indeed revered for his position
- Old Superhero — A '60s superhero, now, in his 60s, who may still be tough and cool, tough or cool, or a parody of such traits
- Older and Wiser — A character older than the heroes whose function is to impart wisdom on how they solved situations similar to what the heroes now face
- Older Is Better — If past times were cooler than the present, then the people who lived there must be equally cool, right?
- The Patriarch — An older male figure who rules over a clan, often unscrupulously
- Perilous Old Fool — An aged person who was a great fighter in their youth, still believes they are and tries to continue, to mixed results
- Retired Badass — Whatever position made the character badass has been retired from... but the traits remain, usually making them a quiet secret badass or someone who is asked to return to their position because of their amazing skills
- Stronger with Age — Someone/thing whose power or skills grow, naturally or mystically but rarely through practice, over many years
- When Elders Attack — An older character has been provoked, often delivering a humorous ass-whooping with improvised weapons
- Yes sir, getting off your lawn now, sir. Please don't hurt me.