Common plecostomus- there actual a few species sometimes labeled "common", but both can reach over 2' in length
Oscars- the tiny oscar you see at the pet store is a BABY and they grow fast. They can reach one foot in their first year, I have had one that was 16".
Pacus, red or black. Sometimes sold as "vegetarian piranhas". Can reach 3 feet and weigh 30 pounds.
Clown Knife- Absolutely gorgeous, I understand wanting to keep them, I want one myself, but they get over 3 feet long and require a minimum of 500 gallons.
Angelfish- They only get about 6 inches long, but get 12 inches tall. 29 gallons minimum for one. A 55 can house a same sex trio or a breeding pair, but most people start with 10 or 20 gallon tanks or want more than one fish.
Silver dollars- They need a school(no less than 5 fish) and they do NOT stay silver dollar size, mine reached 4+ inches and all lived 10 to 12 years.
Tinfoil barbs- another schooling fish but get over 6 inches. With the schooling fish, it's not so much their size as how many you need to keep them stress free and their activity level. Even tiny neon tetras or harlequin rasboras are best off in a 20 gallon or larger.
Number one most common tankbuster? Common or "carnival" goldfish. Get 18 inches long or longer. Can live 20+ years with proper care. The reason "everybody knows" the have short lives is they are usually kept by people that don't know about what is required to keep them properly and for the ones that research AFTER they get it, think about this; if you got it as a cheap prize at a carnival, are you going to want to buy well over $100(even used!) worth of equipment to keep one properly? Since they can reach 18'", even a 55 gallon, which has enough water volume to support one is really too small. The standard 55 gallon tank is less than 13 inches front-to-back, inside measurement. A pond or at least a 75 gallon tank is much better.
One last thing to think about, it is better to have the bigger tank to start with rather than planning to upgrade as the fish needs it. Not only will they grow faster in the bigger tank, sometimes life happens and you might not be able to get that bigger tank when it's needed(experience talking!) You'll enjoy the hobby a lot more if it doesn't stress you out!