|Actor||Connor and Owen Fielding|
- ―Manny Heffley, said as a slur against his family
- ―Manny Heffley, the way Manny says brother
In the movie, he is played by twins Connor and Owen Fielding. Manny is loosely based on Pat Kinney, Jeff Kinney's younger brother.
Manny Heffley is a selfish and spoiled toddler who, if he doesn't get his way, he will do things such as removing all of the electricity at the house except for his room. Greg believes that their parents treat Manny like a prince, but that is far from the truth as they treat him this way out of fear of what he will do to them. He watches a show called "The Snurples," which according to a newspaper sets kids back in social skills and language development (Manny starts speaking gibberish). He has never been a protagonist. Manny has shown that this is true - he has no real friends and never plays with other kids in playgroups, but has imaginary ones and uses these to get out of trouble and get extra food. Despite his seemingly air-headed exterior, Manny has shown that he can be very cunning, deceitful, manipulative, and intelligent for his age in unexpected ways. When Susan let him play on Greg's Net Kritterz account, he figured out how to sell all of his brother's items and change his password. He has also locked out the entire family from watching any TV shows except for his personal favorite cartoons. He also has been shown to speak Spanish in The Long Haul.
Manny has also been characterized as extremely uncaring and holds powerful grudges that has endangered the family on multiple occasions. One of these is shown in Cabin Fever, where he shuts off all the lights as well as the air conditioning to every room except his own just because he wasn't taught how to tie his shoes. This caused the entire family to suffer in cold weather and starvation until Greg finally discovered the scandal.
Manny's unusual personality can however significantly help the Heffley family as a whole. Manny can speak Spanish properly, and that's just from listening to hours of Spanish-English wordbook-CD's that his mother borrowed from the spanish library. He also has an extreme ability of learning new things and abilities, which again, is shown when he learns to speak proper Spanish after just a few hours.
The fact Manny is able to learn perfect Spanish, change Greg's password, the parental lock, and kill all the lights except for his room is quite surprising for a child his age, meaning he is quite intelligent but is still socially awkward.
It is likely that Manny knows about his parents' favoritism towards him, and he takes advantage of this. This includes breaking Greg's gaming console, drawing on his bedroom door, taking a dirty magazine to day care, and twisting the "No Swearing" rule in such a way that he makes money out of it.
Manny also gets anything and everything he wants, and his parents trust his lies to Greg and Rodrick, so that's why they end up getting grounded, even though Manny deserves it.
Manny looks like a small kid with three hairs, rabbit-like teeth and wears a white shirt, black shorts and white shoes. In Diary of a Wimpy Kid: The Long Haul (film), Manny has curly hair, a blue shirt and beige shorts.
- In the first book, after he yells "Bubby" at Greg on the stage, Greg says he's been able to keep that nickname quiet for 5 years, meaning Manny must be around 6 or 7. However, there is a storyline contradiction in Rodrick Rules, where Manny says that he is 3, and again in The Last Straw, where it says Manny has been held back from preschool three or four times, making him around 7 or 8.
- In the online version, Manny is allergic to peaches. Greg also mentions this in The Ugly Truth.
- The only members of the family who do not appear to like him are Aunt Cakey, Greg Heffley and Rodrick Heffley.
- Manny is quite smart, as he knows how to change the password to both Greg's Net Kritterz account, the TV parental locks so he can watch whatever he likes. He also Spanish and the Snurples language fluently relatively fast.
- Manny loves Bitter Apple Spray, so he probably likes sour and bitter food.
- According to The Wimpy Kid Movie Diary, the main reason the producers picked twins was because they felt that twins would be easier to work with (on account that there would a backup should one refuse to cooperate).
- Manny seems to be fond of keeping random animals as pets. In The Long Haul, he is attached to The Heffleys' Pig and repeatedly attempts to get him back. In The Getaway, he attempts three times to keep wild sea animals as pets: first with hermit crabs and snails, second with a baby sea turtle, and third with a Box Jellyfish. Surprisingly, in The Meltdown, he doesn't seem too concerned with the pig being lost.
- He may be modeled after Igdoof's little brother.
- Manny got brand new things when he was a baby, like pacifiers, and his bed looked even newer than Rodrick's.
- Jeff Kinney said that he gave Manny his name because he originally didn't know it was short for Emmanuel. Rather, he thought it was meant to be an ultra-masculine name. "So, I wanted to have this tiny boy have this over-masculine name".
- Manny barely appears in Double Down and only makes a few cameos
For more images see: Manny Heffley/Gallery