Kid Kong

Kid Kong was the biggest star ( arf! ) of Monster Fun, coming in as the first strip of the fisrst issue, and starting out as he meant to go on, causing havoc in his eternal quest for 'nana's, and being scolded by his human friend Granny Smith, a deluded old lady who bought her glasses at the same shop as Mr. Magoo,
He was created by the late, great Robert Nixon, and was his favourite strip to draw, next to Frankie Stein. Kid was immensely ( arf! ) popular, and was Monster Fun's marquee character, being based on a really simple, endlessly adaptable premise.
He also, like a lot of IPC strips, regularly broke the fourth wall, as here where he insults the whole human race:

Or here, where he offers his lunch to his creator:

'Nana's, as you can see, play a big part in Kid Kong, and reached a weird kind of peak, as in the episode where, apparently, Granny takes Kid to Bananas Anonymous to cure his addiction.
Don't have that episode sadly, but here's some other examples, showing Nixon's mastery of size, scale and physical comedy.

Badtime Bedtime Books

Badtime Bedtime Books were a splendiferous idea. They were 'extra' comics stuck in the centre of Monster Fun, being the middle four pages that you had to cut out, fold over to make an eight page book, then sneak upstairs to read under the bedcovers when your parents weren't looking.
They were originally written and drawn by the legendary Leo Baxendale, and unlike usual 'extra' stuff like, say, a Robin story in the back of Batman, actually did feel like you were getting something extra special.
Each story was new and unique, and were usually a lite-horror spin on an old classic or current pop-culture icon ( eg. Robinson Gruesome, Trouser Island, Dr. Poo and the must read with that title I Spy With My Little Guy )
The only semi-regular character was this guy, copy boy Leonard Rottingsocks, who Baxendale originally wanted to call Leonard Rottingcorpse, until dissuaded otherwise:

Far from being something you saved till later, Badtime Badtime Books was probably the strip you turned to first, like an infection that had invaded Monster Fun, it being just that little bit nastier and weirder than the rest of the comic.
For instance, want to sleep well tonight? Don't read Punch & Chewday then.

Here's a great example: Marzipan & The Japes.

Frankie Stein

Probably the most loveable of Monster Fun's inmates, Frankie Stein must've been extremely popular with kids, as IPC seemed to use him everywhere.
Starting in Wham! in 1964, the eternal nice-guy monster was resurrected ( arf! ) in the Bronze Age in short-lived weekly Shiver & Shake, staying on when that mag merged with Whoopee! ( great news next week, chums! ), finally settling as honorary editor of MF, years before another green skinned creature took charge over at 2000AD.
Frankie went through several formats too, from the regular strip here, to newspaper style 'silent' piece Freaky Frankie and breaking the fourth wall strip Frankie's Diary, Frankie's Fun Feature, Frankie's Freaky Fun Page, Frankie Presents Ticklish Allsorts, as well as probably several hundred more. This guy was big.
Wherever he appeared, he was great, a likeable, kind hearted big kid whose anguished creator, Professor Cube, spent every issue trying to kill him. He was drawn by several different artists, but the most memorable have to be Ken Reid, the prince of darkness behind Martha's Monster Makeup, and here, Robert Nixon, whose style defined kid friendly '70's fun.

Creature Teacher

More British stuff, now, as requested. These days, if you came up with a pitch that went: 'It's The Bash Street Kids, but written by H.P. Lovecraft', well, they'd bite your hand off, as well as any other available limbs.
Creature Teacher ran in Monster Fun, a kid's weekly that did exactly what it said on the tin ie. It was full of monsters having fun. Creature Teacher himself, as you'll see, was dragged up from Hell to take charge of Class 3x at Massacre St. School, the worst behaved bunch of kids in Monsterville.
It was drawn by Tom Williams, and is full of exquisite detail that unfortunately the printers of the time weren't always able to show off properly.
It's a bit weird, I s'pose, that this is a British strip where we're supposed to root for the teacher and not the kids, but the way this lot carry on, you wish Creature Teacher would have done with it, and just eat the little bastards.