Dustin Diamond, 37, faces charges of felony second-degree recklessly endangering safety, disorderly conduct, and carrying a concealed weapon.
The fight is said to have happened on Thursday in Port Washington, Wisconsin, while Diamond was with his fiancee.
Crime reports say the pair had been to several bars before they got into a row with two men and another woman.
The fight took place at the Grand Avenue Saloon.
When police caught up with the couple's car near the bar, Diamond told police he had a "pen" in his hand when he grabbed one of the men, according to the criminal complaint.
Officers found a switchblade knife in the car - the point of it appeared to be covered in blood.
Reports say that Diamond later told police he accidentally stabbed the man while he was trying to defend his fiancee - 27-year-old Amanda Schutz.
She also faces a charge of disorderly conduct.
Diamond appeared in Ozaukee County court on Friday and his bail was set at $10,000 (Â£6,425). His next hearing is set for 29 December.
Police said the man who was stabbed was injured in the armpit but is not thought to be seriously hurt.
Representatives for Diamond have not yet commented and the actor is yet to release a formal statement.
Saved by the Bell aired during the 1990s and followed the lives of a group of high school students.
Since the show ended, Diamond has been sued a number of times for failure to pay taxes and in foreclosure proceedings following missed mortgage payments.
He has appeared on reality TV shows, made a sex tape and made a documentary called The Unauthorised Saved by the Bell Story.
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Andy Symonds and Cooper Vuna both went over for the hosts, either side of Neil de Kock's try for the league leaders.
Two tries from Ashton and Samuela Vunisa gave the visitors a 29-14 lead at the break.
Ashton and Ben Ransom touched down after half-time before Vuna claimed his second of the match.
As well as playing in the final of European rugby's elite competition against French Top 14 side Racing 92 in Lyon on 14 May, Saracens must now also prepare for a Premiership semi-final against Leicester Tigers.
Worcester, who have finished 10th in the table, are to follow in Sarries' footsteps by moving from playing on grass to an artificial pitch from the start of next season.
Saracens director of rugby Mark McCall:
"We've led the Premiership for three out of the last four seasons. To get 80 points, without our internationals (who were) away for such a long period is a tremendous achievement, but the best is yet to come as we have a young squad.
"Last week we played poorly in the first half against Newcastle but we were impressive today."
Worcester Warriors director of rugby Dean Ryan:
"They are an outstanding side - we struggled with their power and we need to increase depth in our squad if we are going to improve.
"For the 15 minutes before half-time we were nowhere near, we struggled with our kicking game and kept feeding Alex Goode and we never laid a hand on him.
"It's a stark reminder of the top and where we are. We have to bring more power into our squad."
Warriors: Pennell; Heem, Symons, Mills, Vuna; Heathcote, Baldwin; Leleimalefaga, Annett, Schonert, O'Callaghan, Sanderson, Betty, Kirwan, Dowson (capt).
Replacements: Bregvadze, Bower, Johnston, Hewitt, Cox, Mulchrone, Lamb, Grove.
Saracens: Goode; Ashton, Bosch, Tompkins, Wyles; Hodgson (capt), de Kock; Barrington, George, Du Plessis, Kruis, Hamilton, Wray, Brown, Vunisa.
Replacements: Saunders, Lamositele, Figallo, Smith, Fraser, Spencer, Streather, Ransom.
The actor who played Screech in US TV show Saved by the Bell has been charged with stabbing a man in a bar fight.
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Chris Ashton scored a hat-trick as Saracens prepared for next weekend's European Champions Cup final by comfortably beating Worcester.